Patent Publication Number: US-2023158378-A1

Title: Golf club head with improved inertia performance

Description:
RELATED APPLICATIONS 
     The present application is a continuation of co-pending U.S. application Ser. No. 17/323,591, filed on May 18, 2021, which is a continuation-in-part of co-pending U.S. application Ser. No. 15/931,091, filed on May 13, 2020, which is a continuation-in-part of co-pending U.S. application Ser. No. 16/780,040, filed on Feb. 3, 2020, which is a continuation-in-part of co-pending U.S. application Ser. No. 16/539,622, filed on Aug. 13, 2019, which is a continuation-in-part of abandoned U.S. application Ser. No. 16/219,651, filed on Dec. 13, 2018, the entirety of which are incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a new and improved golf club having improved Moment of Inertia (MOI) characteristics, combined with an improved Center of Gravity (CG) location. More specifically, the golf club head in accordance with the present invention achieves a relative low Moment of Inertia (MOI) about the Z-axis (MOI-Z), a low MOI about the Shaft Axis (MOI-SA), all combined with a high MOI about the X and Y-axis (MOI-X and MOI-Y) and maintaining a consistently and relatively low CG location measured along a direction normal to the hosel axis along the X-Y plane (CG-B). 
     BACKGROUND OF THE INVENTION 
     With the development of the modern day oversized metalwoods, the performance capabilities of these types of golf clubs have increased dramatically over their predecessor, “the persimmon wood”. One of the ways these metalwood type golf clubs have been performing better than their predecessors is in the increase in overall distance, generally attributed to the inherent elastic deformation of thin metallic metal materials used by these metalwoods. Another way the metalwood type golf clubs have been outperforming their predecessors is in the increase in overall forgiveness of the golf club head, generally attributed to the increase in the MOI of the golf club head itself. 
     The MOI of a golf club head generally is a term used to describe the ability of an object to resist rotational movement upon impact with a secondary object. In the case of a golf club head, MOI refers to the ability of the golf club head to resist undesirable twisting upon impact with a golf ball, as such a twisting movement will generally change the face angle of the golf club head away from the intended target line, sending the golf ball away from the intended target. 
     U.S. Pat. No. 5,354,055 to MacKeil shows one of the earliest attempts to increase the MOI of a golf club head by placing the Center of Gravity (CG) location rearward. U.S. Pat. No. 6,364,788 to Helmstetter et al. shows the utilization of weighting members to help control the MOI of the golf club head. Both of these patents refer to the MOI-y of the golf club head, as it relates to the ability of the golf club head to stay stable when encountering an off-center impact in the heel and toe direction. 
     U.S. Pat. No. 7,850,542 to Cackett et al. illustrates a further development in the MOI research wherein a recognition of the different axis of rotation of the different MOI&#39;s. (Alternatively known as Ixx, Iyy, and Izz instead of MOI-X, MOI-Y, and MOI-Z) Despite the recognition and identification of the difference in MOI values, U.S. Pat. No. 7,850,542 only focuses its attention on Ixx and Iyy (adapted and changes to the current reference nomenclature), without any recognition of the importance of the last MOI number, Izz, nor MOI-SA and how they can affect the performance of the golf club. 
     Despite the above, none of the references recognizes the importance of the MOI of the golf club head horizontally forward and aft of the face (MOI-Z), and ways to design a golf club that takes advantage of the performance characteristics of golf club with more optimal MOI-Z values along with the minimized MOI-Sa values. Moreover, a closer investigation of the MOI-Z values will yield CG locations that will work in conjunction with the above MOI-Z values to create more performance. Hence, it can be seen from the above there is a need for more research and a design of a golf club capable of achieving better performance by investigating the importance of MOI-Z and MOI-SA as well as the CG location and designing a golf club head. 
     BRIEF SUMMARY OF THE INVENTION 
     One aspect of the present invention is a golf club comprised of a golf club head, a shaft coupled to the golf club head at a first end of the shaft and a grip coupled to the shaft at a second end of the shaft, where the golf club head comprises of a frontal portion further comprising a striking face that defines a face center, located at a forward portion of the golf club head; a rear portion located aft of the striking face; and at least one weighting member located near a central portion of the golf club head in a heel to toe orientation, substantially in line with and behind the face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a vertical axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards a frontal portion of said golf club head, and wherein said golf club head has a MOI-Y to MOI-Z ratio of greater than about 1.50. 
     In another aspect of the present invention is a golf club head comprising of a golf club head comprising of a frontal portion further comprising a striking face that defines a face center, located at a forward portion of the golf club head, a rear portion located aft of the striking face, and at least one weighting member located near a central portion of the golf club head in a heel to toe orientation, substantially in line with and behind the face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a horizontal axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards a frontal portion of said golf club head, and wherein said golf club head has a MOI-X, MOI-Z, and CG-Z numbers that satisfies the equation 
     
       
         
           
             
               
                 MOI 
                 - 
                 X 
               
               
                 MOI 
                 - 
                 Z 
               
             
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                 ( 
                 
                   
                     6 
                     . 
                     7 
                   
                   ⁢ 
                   5 
                   ⁢ 
                   0 
                   ⁢ 
                   1 
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                   CG 
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                   Z 
                 
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               - 
               
                 9 
                 ⁢ 
                 
                   9 
                   . 
                   3 
                 
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                   0 
                   . 
                 
               
             
           
         
       
     
     Another aspect of the present invention is a golf club head comprising a striking face, a crown return, a sole return and a central body member that are formed of metal. The central body member is located near the central portion of said golf club head in a heel to toe orientation, substantially in line along the z-axis, and extends from the crown return and the sole return to a back edge of said golf club. 
     Preferably, the golf club head is further comprised of a heel body member made of a non-metallic material and coupled to a heel side of the central body member and a toe body member made of a non-metallic material and coupled to a toe side of the central body member. The golf club head can further include two weight members, one forward near the striking face and one aft near the back edge. In one embodiment, a wall member is coupled to a crown portion of the central body member and a sole portion of the central body member and extends between the first and second weight members. 
     In another embodiment, the golf club head is further comprised of a central support member that is comprised of a plurality of angled strut members extending form the crown to the sole between the two weight members. Preferably, a first angled strut member extends from a crown portion of the central body member to the sole and a second angled strut member extends from a sole portion of the central body member to the crown, and the first and second angled strut members cross each other. More preferably, the first and second angled strut members extend at an angle of between 15 degrees and 75 degrees from both the y-axis and the z-axis. The golf club head can further comprise a third angled strut member that extends from a crown portion of the central body member to the sole and a fourth angled strut member that extends from a sole portion of the central body member to the crown, and the third and fourth angled strut members cross each other. The third and fourth angled strut members also extend at an angle of between 15 degrees and 75 degrees from both the y-axis and the z-axis, and preferably, the third angled strut member is coupled to the first angled strut member and the fourth angled strut member is coupled to the second angled strut member. The golf club can further comprise a vertical strut member extending vertically, substantially parallel to the y-axis, between the fourth angled strut member and the third angled strut member. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
         FIG.  1    of the accompanying drawings shows a perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG.  2    of the accompanying drawings shows a top view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG.  3    of the accompanying drawings shows a frontal view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG.  4    of the accompanying drawings shows a plot of MOI-Z vs MOI-Y numbers for the current invention, compared to prior art golf club heads; 
         FIG.  5    of the accompanying drawings shows a plot of MOI-Z vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads; 
         FIG.  6    of the accompanying drawings shows a plot of MOI-Y vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads; 
         FIG.  7    of the accompanying drawings shows a plot of MOI-X vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads; 
         FIG.  8    of the accompanying drawings shows a plot of MOI-Z vs CG-B/Face Width numbers for the current invention, compared to prior art golf club heads; 
         FIG.  9    of the accompanying drawings shows a plot of MOI-Z vs CG-B/Head Width numbers for the current invention, compared to prior art golf club heads; 
         FIG.  10    of the accompanying drawings shows a plot of MOI-X/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads; 
         FIG.  11    of the accompanying drawings shows a plot of MOI-Y/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads; 
         FIG.  12    of the accompanying drawings shows a plot of (MOI-X+MOI-Y)/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads; 
         FIG.  13    of the accompanying drawings shows an exploded sole perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG.  14    of the accompanying drawings shows a horizontal cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG.  15    of the accompanying drawings shows a vertical cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG.  16    of the accompany drawings shows a perspective view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  17    of the accompanying drawings shows a top view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  18    of the accompanying drawings shows a frontal view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  19    of the accompanying drawings shows a horizontal cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  20    of the accompanying drawings shows a vertical cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  21    of the accompanying drawings shows a top view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  22    of the accompanying drawings shows a frontal view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  23    of the accompanying drawings shows a top view of a body portion of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  21   ; 
         FIG.  24    of the accompanying drawings shows a bottom view of a body portion of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  21   ; 
         FIG.  25    of the accompanying drawings shows a vertical side view of a body portion of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  26    of the accompanying drawings shows a vertical side view of a body portion of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  27    of the accompanying drawings shows a top view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  28    of the accompanying drawings shows a top view of a body portion of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  27   ; 
         FIG.  29    of the accompanying drawings shows a bottom view of a body portion of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  27   ; 
         FIG.  30    of the accompanying drawings shows a top view of a body portion of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  27   ; 
         FIG.  31    of the accompanying drawings shows a bottom view of a body portion of the golf club head in accordance with an alternative embodiment of the present invention; 
         FIG.  32    of the accompanying drawings shows a cross-sectional view of a first weight member shown in  FIG.  31   ; 
         FIG.  33    of the accompanying drawings shows a cross-sectional view of a second weight member shown in  FIG.  31   ; 
         FIG.  34    of the accompanying drawings shows a bottom perspective view of another embodiment of a golf club head in accordance with the present invention; 
         FIG.  35    of the accompanying drawings shows a cross-sectional view of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  34   ; 
         FIG.  36    of the accompanying drawings shows a close-up, cross-sectional view of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  34   ; 
         FIG.  37    of the accompanying drawings shows a close-up, cross-sectional view of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  34   ; 
         FIG.  38    of the accompanying drawings shows a bottom perspective view of another embodiment of a golf club head rear portion in accordance with the present invention; 
         FIG.  39    of the accompanying drawings shows a frontal view of the golf club head rear portion in accordance with an alternative embodiment of the present invention shown in  FIG.  38   ; 
         FIG.  40    of the accompanying drawings shows a close-up, cross-sectional view of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  38   ; 
         FIG.  41    of the accompanying drawings shows a close-up, cross-sectional view of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  38   ; 
         FIG.  42    of the accompanying drawings shows a bottom perspective view of another embodiment of a golf club head in accordance with the present invention; 
         FIG.  43    of the accompanying drawings shows a cross-sectional view of the golf club head in accordance with an alternative embodiment of the present invention shown in  FIG.  42   ; 
         FIG.  44    of the accompanying drawings shows an exploded perspective view of another embodiment of a golf club head in accordance with the present invention; 
         FIG.  45    of the accompanying drawings shows an exploded perspective view of another embodiment of a golf club head and mold in accordance with the present invention; 
         FIG.  46    of the accompanying drawings shows a rear weight member for another embodiment of a golf club head in accordance with the present invention; 
         FIG.  47    of the accompanying drawings shows an exploded perspective view of the rear weight member in  FIG.  46   ; 
         FIG.  48    of the accompanying drawings shows a rear weight member for another embodiment of a golf club head in accordance with the present invention; 
         FIG.  49    of the accompanying drawings shows a rear weight member and a golf club head in accordance with the present invention; 
         FIG.  50    of the accompanying drawings shows a rear weight member and a golf club head in accordance with the present invention; 
         FIG.  51    of the accompanying drawings shows a rear weight member and a golf club head in accordance with the present invention; 
         FIG.  52    of the accompanying drawings shows a rear weight member and a golf club head in accordance with the present invention; 
         FIG.  53    of the accompanying drawings shows a rear weight member and a golf club head in accordance with the present invention; 
         FIG.  54    of the accompanying drawings shows a rear weight member and a golf club head in accordance with the present invention; 
         FIG.  55    of the accompanying drawings shows a rear weight member and a golf club head in accordance with the present invention; and 
         FIG.  56    of the accompanying drawings shows the rear weight member of the golf club in  FIG.  55   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description describes the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
     Various inventive features are described below and each can be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
     Before beginning the discussion on the current inventive golf club head and its performance criteria, it is worthwhile to note here that the discussion below will be based on a coordinate system  101  and axis of measurement that is critical to the proper valuation of the performance numbers. Hence, it is important to recognize here that although the specific names given for the measurements below are important to the understanding of the current invention, the naming nomenclature should not be viewed in vacuum. Rather, the importance is the numbers presented below needs to be taken in context with how the coordinate system relates to the golf club head itself. In order to provide sufficient information to avoid any ambiguity, each of the figures provided below referencing a golf club head will all be accompanied by a coordinate system that is all consistent with one another. 
     Pursuant to the above, and to establish the reference coordinate system for the subsequent discussion,  FIG.  1    of the accompanying drawings shows the coordinate system  101  that will be used to define the various measurement and performance figures for the current invention. The x-axis used by the current discussion refers to the axis that is horizontal to the striking face from a heel to toe direction. The y-axis used by the current discussion refers to the vertical axis through the club in a crown to sole direction. The z-axis used by the current discussion refers to the horizontal axis that is horizontal front to back in a forward and rear direction. Alternatively speaking, it can be the x-axis is defined as a horizontal axis tangent to a geometric center of the striking face with the positive direction towards a heel of the golf club head, a y-axis is a horizontal axis orthogonal to the x-axis with a positive direction towards a top of the golf club head, and a z-axis being orthogonal to both the x-axis and the y-axis with a positive direction towards a front of the golf club head. The x-y-z coordinate system described above shall be the same for all subsequent discussions. 
       FIG.  1    of the accompanying drawings shows a perspective view of a golf club head  100  in accordance with an embodiment of the present invention. In this perspective view shown in  FIG.  1   , the golf club head  100  may not look very different than other golf club heads, but the subsequent figures and discussion will show that the internal components and the material properties of this golf club head  100  allows it to achieve unique performance properties consistent with the present invention. What  FIG.  1    does show is a location of a face center  102  of the frontal portion  104  of the golf club head  100  that contains a striking face insert. The face center, as shown here and referred to by the current invention, relates to the geometric center of the striking face portion of said golf club head  100  measured by the USGA provided face center template as it would be commonly known to a person of ordinary skill in the golf club art. Attached to the rear of the frontal portion  104  is a rear portion  106 , which makes up the back end of the golf club head  100 . 
     In this embodiment of the present invention, the frontal portion  104  may generally be made out of a steel type material having a density of between about 7.75 g/cc and about 8.00 g/cc, allowing a significant portion of the mass of the golf club head  100  to be concentrated at a frontal bottom region of the golf club head  100 . The rear portion  106  of the golf club head  100  in this embodiment of the present invention may generally be made out of the standard titanium material having a density of between about 4.00 g/cc and about 5.00 g/cc, allowing the rear portion  106  of the golf club head  100  to be relatively lightweight. However, it should be noted that in alternative embodiments of the present invention, the frontal portion  104  may also be made out of a standard titanium material such as TI-6-4, Ti-8-1-1, beta-titanium, or any other type of titanium material without departing from the scope and content of the present invention. 
     In order to illustrate more specific features of the golf club head  100 ,  FIGS.  2  and  3    of the accompanying drawings is provided to give more insight into some of the specific inherent characteristics of the golf club head  200  that will be important to determine its improved performance. First off,  FIG.  2    of the accompanying drawings, in addition to illustrating a golf club head  200  with a frontal portion  204  and a rear portion  206 , also shows a Center of Gravity (CG)  210  location along the x-z plane on the coordinate system  201 . Although the details of the CG location will be discussed in more detail with respect to the inertia properties of the golf club head  200 , the general direction of the current inventive golf club head  200  is to have a CG location that is strategically located at a distance back from the frontal portion of the golf club head  200  to yield the most advantageous results. 
     More specifically, in the current invention, the CG location rearward from the striking face, identified here as CG-Z is generally between about 25 mm to about 40 mm, more preferably between about 26 mm and about 38 mm, and most preferably between about 27 mm and about 36 mm, all measured rearward from the face center  202  along the Z axis shown by the coordinate system  201 . In addition to illustrating the CG-Z  212  numbers, an alternative measurement method is provided to measure how far back the CG  210  is located within the club head  200 . In this alternative method, the CG  210  is measured from the shaft axis  215 , and this measurement is illustrated as CG-C  214  is generally measured to be between about 10 mm to about 25 mm, more preferably between about 12 mm to about 23 mm, and most preferably between about 14 mm to about 21 mm, all measured rearward from the shaft axis  215  along the Z axis shown by the coordinate system  201 . 
     It should be noted that the strategic location of the CG  210  location rearward along the Z axis, irrespective of whether it is measured from the face center  202  or the shaft axis  215 , is critical to the proper functionality of the current inventive golf club head  200 . If the CG  210  location is too far forward, the golf club head  200  can result in a low MOI-X and MOI-Y as well as too low of a backspin when contacting a golf ball to yield desirable results. However, in the alternative, if the CG  210  location is too far rearward, the golf club head  200  can produce too much spin to yield desirable results. Hence, it can be seen that the criticality of the CG location rearward of along the Z axis is a fine balance of a very specific range of numbers that can severely hinder the performance of the golf club head  200  if it deviates from the ranges articulated above. 
       FIG.  3    of the accompanying drawings shows another important CG  210  measurement that is important to the proper functionality of the current invention. More specifically,  FIG.  3   , in addition to illustrating all of the basic components of the golf club head  200  as previously shown, now introduces another measurement of the CG  210  location from the shaft axis  215  along an x-y plane shown by coordinate system  301 . More specifically,  FIG.  3    shows a CG  210  measurement that is perpendicular to the shaft axis  215  along this x-y plane away from the actual shaft axis  215  itself, called CG-B for the purpose of this application. The CG-B of the golf club head  210  may generally be between about 32 mm and about 39 mm, more preferably between about 33 mm and about 38 mm, and most preferably about 35 mm. 
     In addition to illustrating the very important CG-B measurement of the golf club head,  FIG.  3    of the accompanying drawings also shows measurements W 1  and W 2 , indicative of the width of the golf club head  200  itself and the width of the face of the golf club head  200  respectively. In this embodiment of the present invention, the width of the golf club head W 1  may generally be between about 130 mm to and about 140 mm, more preferably between about 132 mm to about 138 mm, and most preferably about 136 mm. The width of the face W 2  may generally be between about 95 mm and about 105 mm, more preferably between about 97 mm and about 103 mm, and most preferably about 100 mm. 
     Now that the CG location of the golf club head  200  has been defined, the other important features associated with the present invention relates to the Moment of Inertia (MOI) of the golf club head  200 . The MOI of a golf club head generally depicts the ability of the golf club head to resist twisting when it impacts an object at a location that is not aligned with the CG location previously discussed. More specifically, the MOI of a golf club head relates to the ability of the golf club head to resist twisting relative to the CG location. The MOI of the golf club head  200  may generally be broken down to three unique components, relating to the ability of the golf club head  200  to resist rotation along three different axes. The three axes of rotation for which the MOI is generally referred coincides with the coordinate system  101 ,  201 , and  301  (shown in  FIG.  1   ,  FIG.  2   , and  FIG.  3    respectively). 
     As the previously discussion already hinted, the current inventive golf club head  200  may generally have a high value for the MOI about the X and Y axis, while maintaining a low MOI about the Z axis. More specifically, the current inventive golf club head  200  may generally have a MOI about the X axis (MOI-X) that is greater than about 300 kg-mm 2 , more preferably greater than about 310 kg-mm 2 , and most preferably greater than about 320 kg-mm 2  without departing from the scope and content of the present invention. As for MOI about the Y axis (MOI-Y), the present inventive golf club head  200  may generally have a MOI about the Y axis that is greater than about 400 kg-mm 2 , more preferably greater than about 410 kg-mm 2 , and most preferably greater than about 420 kg-mm 2  all without departing from the scope and content of the present invention. 
     While the large MOI number about the X and Y axis discussed previously are not necessarily new in the world of golf club head  200  designs, the ability to maintain those number while decreasing the MOI about the Z axis (MOI-Z) and holding the MOI about the Shaft axis (MOI-SA) to a minimum is what makes the present invention. While the majority of the golf industry are focusing their attention so intently on the ability of the golf club head  200  to offer forgiveness on off center hits by trying to increase the MOI-Y to astronomical numbers, they have failed to recognize the ability of the golf club head  200  to offer more club head speed and more ball speed by decreasing the MOI about the Z axis (MOI-Z) in concert with the minimization of MOI about the Shaft axis (MOI-SA). The present invention focuses its attention on that very specific unrecognized characteristic, and has developed a golf club head  200  design to take advantage and maximize the performance of the golf club head  200  by focusing on the MOI about the Z axis. More specifically, a golf club head  200  in accordance with the present invention may generally have a MOI about a Z axis that is less than about 268 kg-mm 2 , more preferably less than about 260 kg-mm 2 , and most preferably less than about 250 kg-mm 2 . Additionally, the golf club head  200  may generally have a MOI about a Shaft axis that is less than about 850 kg-mm 2 . 
     It should be noted here that the low MOI-Z numbers mentioned above cannot by itself accurately depict and describe the current invention; as old school golf club heads with much smaller footprint may inherently have a low MOI-Z number, combined with a low MOI-X and MOI-Y number. Hence, it is important to recognize here that the present invention is predicated on the interrelationship between the different numbers achieved by the MOI-X and MOI-Y numbers as it relates to MOI-Z and MOI-SA, in combination with the CG location articulated above. 
     In order to capture the essence of the present invention, a ratio can be created between the MOI-X, MOI-Y, and MOI-Z to help provide one way to quantify this relationship. In one first example, a MOI-X to MOI-Z Ratio can be created to help quantify the current golf club head  200  as illustrated by Eq. (1) below. In one exemplary embodiment of the present invention, the MOI-X to MOI-Z Ratio is greater than about 1.10, more preferably greater than about 1.20, and most preferably greater than about 1.28. 
     
       
         
           
             
               
                 
                   
                     MOI 
                     - 
                     X 
                     ⁢ 
                         
                     to 
                     ⁢ 
                         
                     MOI 
                     - 
                     Z 
                     ⁢ 
                         
                     Ratio 
                   
                   = 
                   
                     
                       MOI 
                       - 
                       X 
                     
                     
                       MOI 
                       - 
                       Z 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                       
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
     
     Similarly, a comparable ratio can be established called a MOI-Y to MOI-Z Ratio to quantify the current golf club head  200  as illustrate by Eq. (2) below. In one exemplary embodiment of the present invention, the MOI-Y to MOI-Z ratio is greater than about 1.50, more preferably greater than about 1.57, and most preferably greater than about 1.68. 
     
       
         
           
             
               
                 
                   
                     MOI 
                     - 
                     Y 
                     ⁢ 
                         
                     to 
                     ⁢ 
                         
                     MOI 
                     - 
                     Z 
                     ⁢ 
                         
                     Ratio 
                   
                   = 
                   
                     
                       MOI 
                       - 
                       Y 
                     
                     
                       MOI 
                       - 
                       Z 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                       
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
       
     
     As it can be seen from the relationship established by the Eqs (1) and (2) above, the present invention relates to a specific relationship between the MOI of the golf club head  200  with an extra focus on minimizing the MOI-Z about the Z axis while maintaining a high MOI-Y. In order to further illustrate this, a graphical representation of the relationship is provided as  FIG.  4   . 
       FIG.  4    of the accompanying drawings shows a plot of various data points of various golf club head and their respective MOI-Z numbers as well as their MOI-Y number. In  FIG.  4    the X-axis represents the MOI-Y while the Y-axis represents the MOI-Z. The data points shown in  FIG.  4    have been separated into circular dots and asterisks. The circular dots are representative of the data of “prior art” golf club heads, whereas the asterisk data points represent the current invention. 
     A closer examination of the prior art data points will show that none of the golf club heads in the prior art are capable of achieving a MOI-Z number of lower than 268 kg-mm 2 , for all modern day golf club heads that have a MOI-Y of greater than 420 kg-mm 2 . However, an even closer examination of the graph of  FIG.  4    will show that as the MOI-Y numbers of the golf club heads exceeds 500 kg-mm 2 , an additional relationship can be established to quantify the ability of the present invention to achieve the optimal MOI-Z to MOI-Y relationship. In fact, that relationship is shown in  FIG.  4    as Y≤0.47x+33. Combining the two conditions articulated above can result in another unique way to quantify the present invention whereas, for golf club heads having a MOI-Y of between 420 kg-mm 2  and 500 kg-mm 2 , the golf club head generally has a MOI-Z of less than about 268; however, for golf club heads having a MOI-Y of greater than 500 kg-mm 2 , the golf club head may have a MOI-Z that satisfies Eq. (3) below: 
       MOI- Z ≤(0.47*MOI- Y )+33  Eq. (3)
 
     Alternatively speaking, it can be said that in one embodiment of the present invention, the golf club head  200  may have a MOI-Z that satisfies the relationship MOI-Z≤(0.47*MOI-Y)+33 if the MOI-Y number is greater than 500 kg-mm 2 , and a MOI-Z that is less than 268 kg-mm 2  if the MOI-Y number is between 420 kg-mm 2  and 500 kg-mm 2 . 
       FIG.  5    of the accompanying drawing introduces another MOI value relating to a golf club head not previously discussed named MOI-Shaft Axis (MOI-SA). The MOI of a golf club head as it relates to the shaft axis is defined as the ability of the golf club head to resist twisting upon impact with a golf ball at a location that is not aligned with the shaft axis. A golf club head in accordance with the present invention may generally have a MOI-SA of less than about 850 kg-mm 2 , more preferably less than about 800 kg-mm 2 , and most preferably less than about 750 kg-mm 2 . The relationship between the MOI-SA and MOI-Z is highlighted in  FIG.  5    and is important to the present invention.  FIG.  5    of the accompanying drawings shows that irrespective of the MOI-SA numbers, all of the prior art golf club heads have a MOI-Z of greater than about 268 kg-mm 2 , while all of the current inventive golf club heads have a MOI-Z of less than about 268 kg-mm 2 . 
       FIG.  6    of the accompanying drawings establishes a graphical relationship between the MOI-Y of the golf club head with the newly introduced MOI-SA. As a closer examination of the graph shown in  FIG.  6    will show, the current invention is capable of achieving a higher than average MOI-Y, all while keeping a relatively small MOI-SA. Similar to previous plots, the circular points on the plot will refer to prior art golf club heads, while the asterisks will refer to the current invention. Hence, it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≥0.52x+147, which when put into context with the variables used in this plot, yields Eq. (4) below: 
       MOI- Y ≥(0.52*MOI- SA )+147  Eq. (4)
 
       FIG.  7    of the accompanying drawings establishes a graphical relationship between the MOI-X of the golf club head with now a familiar MOI-SA. As a closer examination of the graph shown in  FIG.  7    will show, the current invention is capable of achieving a higher than average MOI-X, all while keeping a relatively small MOI-SA. Hence, it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≥0.40x+50, which when put into context with the variables used in this plot, yields Eq. (5) below: 
       MOI- X ≥(0.40*MOI- SA )+50  Eq. (5)
 
       FIG.  8    of the accompanying drawings establishes a graphical relationship between the MOI-Z of the golf club head with a ratio of CG-B/Face Width. Both the measurement for CG-B and Face Width can be found in  FIG.  3    of the accompanying drawings as well as the accompanying discussion in paragraphs [0022] and [0023]. The CG-B measurement is explicitly shown in  FIG.  3   , while the Face Width referred to by the chart in  FIG.  8    is shown as W 2 . A closer examination of the graph shown in  FIG.  8    will show that the current invention is capable of achieving a lower MOI-Z, while keeping the CG-B/Face Width number fairly consistent above 0.4. CG-B/Face Width is indicative of the location of the center of gravity while keeping a moderately sized face golf club head. 
     In the chart shown in  FIG.  8   , it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≤1000x−150, which when put into context with the variable used in this plot, yields Eq. (6) below: 
     
       
         
           
             
               
                 
                   
                     MOI 
                     - 
                     Z 
                   
                   ≤ 
                   
                     
                       ( 
                       
                         1000 
                         * 
                         
                           
                             CG 
                             - 
                             B 
                           
                           
                             Face 
                             ⁢ 
                                 
                             Width 
                           
                         
                       
                       ) 
                     
                     - 
                     150 
                   
                 
               
               
                 
                   Eq 
                   . 
                       
                   
                     ( 
                     6 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG.  9    of the accompanying drawings establishes a graphical relationship between the MOI-Z of the golf club head with a ratio of CG-B/Head Width. Both the measurement for CG-B and Head Width can be found in  FIG.  3    of the accompanying drawings as well as the accompanying discussion above in paragraph [0022] and [0023]. The CG-B measurement is explicitly shown in  FIG.  3   , while the Head Width referred to by the chart in  FIG.  9    is shown as W 1 . A closer examination of the graph shown in  FIG.  9    will show that the current invention is capable of achieving a lower MOI-Z, while keeping the CG-B/Head Width number fairly consistent above 0.34. CG-B/Head Width is indicative of the location of the center of gravity while keeping a moderately sized head width of the golf club head. 
     In the chart shown in  FIG.  9   , it can be seen that the present invention occupies a previously unachieved space delineated by a MOI-Z number that is lower than 320 kg-mm 2  combined with a CG-B/Head Width number that is greater than about 0.34. 
       FIG.  10    of the accompanying drawings establishes another graphical relationship of the performance of a golf club in accordance with an embodiment of the present invention. More specifically,  FIG.  10    of the accompanying drawings shows a relationship between MOI-X/MOI-Z and CG-Z. (MOI-X is used interchangeably with Ixx, MOI-Y is used interchangeably with Iyy, and finally MOI-Z is used interchangeably with Izz) The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to  FIG.  2    of the accompanying drawings, while the background information establishing MOI-X and MOI-Z have already been discussed previously. Although the selection of the plot for the X and Y axis may appear random initially to a person not versed in golf club design, but a closer examination will reveal that the relationship created here is absolutely critical to the proper performance of the present invention. On the Y axis of the plot shown in  FIG.  10   , a ratio between MOI-X and MOI-Z is created here. This ratio created illustrates the ability of the current inventive golf club head to maximize the value of one variable (MOI-X) while minimizing the value of another variable (MOI-Z); which resonates with the theme of the present invention. The MOI-Z used in the X axis of the plot shown in  FIG.  10    is indicative of the CG location of the golf club head rearward from the front of the golf club head, and it is desirable to maintain that in the range described above. 
     A further examination of the plot shown in  FIG.  10    will show that the present invention occupies a portion of the graph that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥6.7501x−99.3, which when put into context with the variable used in this plot, yields Eq. (7) below: 
     
       
         
           
             
               
                 
                   
                     
                       MOI 
                       - 
                       X 
                     
                     
                       MOI 
                       - 
                       Z 
                     
                   
                   ≥ 
                   
                     
                       ( 
                       
                         
                           6 
                           . 
                           7 
                         
                         ⁢ 
                         5 
                         ⁢ 
                         0 
                         ⁢ 
                         1 
                         * 
                         CG 
                         - 
                         Z 
                       
                       ) 
                     
                     - 
                     
                       9 
                       ⁢ 
                       
                         9 
                         . 
                         3 
                       
                       ⁢ 
                       0 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                       
                   
                     ( 
                     7 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG.  11    of the accompanying drawings establishes another graphical relationship of a golf club in accordance with an embodiment of the present invention by creating a relationship between the MOI-Y/MOI-Z and CG-Z. The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to  FIG.  2    of the accompanying drawings, while the background information establishing MOI-Y and MOI-Z have already been discussed previously. Similar to the previous discussion, the relationship between MOI-Y and MOI-Z is indicative of the ability of a golf club to achieve great forgiveness along the MOI-Y axis, while minimizing the MOI-Z of a golf club head to achieve a higher ball speed, as previously discussed. Similar to previous discussion,  FIG.  11    of the accompanying drawings shows that the present invention is capable of achieving performance characteristics that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥11.349 x−175.76, which when put into context with the variable used in this plot, yields Eq. (8) below: 
     
       
         
           
             
               
                 
                   
                     
                       MOI 
                       - 
                       Y 
                     
                     
                       MOI 
                       - 
                       Z 
                     
                   
                   ≥ 
                   
                     
                       ( 
                       
                         1 
                         ⁢ 
                         
                           1 
                           . 
                           3 
                         
                         ⁢ 
                         4 
                         ⁢ 
                         9 
                         * 
                         CG 
                         - 
                         Z 
                       
                       ) 
                     
                     - 
                     
                       1 
                       ⁢ 
                       7 
                       ⁢ 
                       
                         5 
                         . 
                         7 
                       
                       ⁢ 
                       6 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                       
                   
                     ( 
                     8 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG.  12    of the accompanying drawings establishes another graphical relationship of a golf club in accordance with an embodiment of the present invention by creating a relationship between the (MOI-X+MOI-Y)/MOI-Z and CG-Z. The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to  FIG.  2    of the accompanying drawings, while the background information establishing MOI-X, MOI-Y, and MOI-Z have already been discussed previously. Similar to the previous discussion, the relationship between MOI-X, MOI-Y, and MOI-Z is indicative of the ability of a golf club to achieve great forgiveness along both the MOI-X and MOI-Y axes, while minimizing the MOI-Z of a golf club head to achieve a higher ball speed, as previously discussed. Similar to previous discussion,  FIG.  12    of the accompanying drawings shows that the present invention is capable of achieving performance characteristics that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥18.67 x−296.63, which when put into context with the variable used in this plot, yields Eq. (9) below: 
     
       
         
           
             
               
                 
                   
                     
                       ( 
                       
                         
                           MOI 
                           - 
                           X 
                         
                         + 
                         
                           MOI 
                           - 
                           Y 
                         
                       
                       ) 
                     
                     
                       MOI 
                       - 
                       Z 
                     
                   
                   ≥ 
                   
                     
                       ( 
                       
                         1 
                         ⁢ 
                         
                           8 
                           . 
                           6 
                         
                         ⁢ 
                         7 
                         * 
                         CG 
                         - 
                         Z 
                       
                       ) 
                     
                     - 
                     
                       2 
                       ⁢ 
                       9 
                       ⁢ 
                       
                         6 
                         . 
                         6 
                       
                       ⁢ 
                       3 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                       
                   
                     ( 
                     9 
                     ) 
                   
                 
               
             
           
         
       
     
       FIGS.  13  through  15    show different exploded and cross-sectional view of golf club heads and their internal components that are used to achieve the performance characteristics described above.  FIG.  13    shows an exploded perspective view of an exemplary design of a golf club head  1300  in capable of achieving the performance characteristics previously discussed. The golf club head  1300  is made out of the essential components previously discussed in  FIG.  1    in terms of a frontal portion  1304  and a rear portion  1306 . However, this exploded view of golf club head  1300  allows additional components to be shown in more detail. More specifically,  FIG.  13    illustrates that, as often the case in a golf club head construction, the frontal portion  1302  may further be comprised out of a separate component called the striking face insert  1320  to form the striking portion of the golf club head  1300 . The rear portion  1306  of the golf club head  1300  is where it gets more interesting. In order to achieve the performance numbers above of a higher MOI-Y, a higher MOI-X, and a lower MOI-Z, a significant amount of mass is re-allocated towards the center of the golf club head away from the perimeter. In order to achieve this, the present invention utilizes four weighting members that are all comprised out of a high density material that have a higher density than the frontal portion  1302  or the rear portion  1306 . The four weighting members can be separated into a frontal sole weight  1322 , frontal internal weight  1324 , rear internal weight  1326 , and rear sole weight  1328 , and these weighting members may all generally have a material density of greater than 13 g/cc, more preferably greater than about 15 g/cc, and most preferably greater than or about 17 g/cc. 
     It should be noted that in this exemplary embodiment of the present invention, all of the weighting members  1322 ,  1324 ,  1326 , and  1328  are all made out of the same material having the same heavy density discussed previously. However, in alternative embodiments of the present invention, different densities of tungsten may be used for different weighting members depending on the design criteria and desired CG location all without departing from the scope and content of the present invention. 
       FIG.  14    of the accompanying drawings shows a cross-sectional view of a golf club head  1400  in accordance with an exemplary embodiment of the present invention. The cross-sectional view of the golf club head taken across a horizontal plane across the face of the golf club head  1400  to allow some of the relationship between the golf club head  1400  and the various weighting member  1422 ,  1424 ,  1426 , and  1428  to be shown more clearly. In addition to the weighting members, the cross-sectional view of the golf club head  1400  shown in  FIG.  14    also allows the face center  1402  and the CG location  1410  to be re-introduced as it relates to the weighting members. It can be seen from this view that at least one weighting member is located near a central portion of the golf club head in a heel to toe direction, and substantially in line with and behind said face center. 
       FIG.  15    of the accompanying drawings shows a cross-sectional view of a golf club head  1500  in accordance with an exemplary embodiment of the present invention taken along a vertical plane that passes through the center of the face. This cross-sectional view of the golf club head  1500  shown in  FIG.  15    provides a little more information on the interworking relationship between the components. More specifically,  FIG.  15    shows a striking face insert  1520  being located in the frontal portion  1504  of the golf club head  1500 . In addition to the above,  FIG.  15    also shows that the frontal sole weight  1522  is located in a receptacle that is created within the frontal portion  1504 . Although not shown in this cross-sectional view in  FIG.  15   , the frontal internal weight is also located in the frontal portion  1504 . Attached to the rear of the frontal portion  1504  is the rear portion  1506 . The rear portion  1506  forms the aft body portion of the golf club head  1500 , and contains the rear internal weight  1526  and the rear sole weight  1528 . These weighting members, combined with the unique materials used to form the frontal portion  1504  and the rear portion  1506 , allow the golf club head  1500  to achieve the unique performance characteristics outlined previously. 
       FIGS.  16  through  20    show various perspective and cross-sectional views of a golf club head  1600  in accordance with an alternative embodiment of the present invention that is capable of achieving the performance goals previously mentioned. Similar to the previous embodiment illustrated by  FIGS.  1 - 3  and  13 - 15   , a lot of weighting member is located near the center of the golf club head  1600  in a heel to toe orientation along the x-axis behind the face center  1602  to help minimize the MOI-Z of the golf club head  1600 . 
     More specifically,  FIG.  16    of the accompanying drawings shows a perspective view of a golf club head  1600  in accordance with this alternative embodiment of the present invention. Although not much can be gleamed from this perspective view of the golf club head  1600 , it does lay the groundwork for the subsequent discussion relating to this particular embodiment of the present invention. Finally,  FIG.  16   , similar to previous figures that illustrate a golf club head, provides a coordinate system  1601  to guide the subsequent discussions. 
       FIG.  17    of the accompanying drawings shows a top view of a golf club head  1600  in accordance with this alternative embodiment of the present invention. In this top view, a couple of familiar dimensions are reintroduced here. First and foremost, the top view of the golf club head  1600  shown in  FIG.  17    allows the relationship between the face center  1602  and the CG  1610  to be shown in more detail. When measured along the Z-axis, the measurement CG-Z is shown as  1612 . The location of the CG, when referenced against the shaft axis  1615  yields another way to measure the CG location along the Z-axis called CG-C  1614 . The number ranges for the CG-Z  1612  and CG-C  1614  measurements are not much different from previous discussions, but this embodiment of the present invention provides an alternative way to achieve those targets with a slightly different construction without the need for a multi-material chassis. 
       FIG.  18    of the accompanying drawings shows a frontal view of a golf club head  1600  in accordance with this alternative embodiment of the present invention. In this frontal view, we can see another feature utilized by the present embodiment to help achieve the performance criteria of the current invention. More specifically,  FIG.  18    shows that in this embodiment of the present invention, in order to minimize the MOI-Z of the golf club head  1600 , weight is removed from the extremities of the golf club head  1600  via a reshaping of the contour at the toe portion of the golf club head  1600 . This reshaping of the contour at the toe portion of the golf club head  1600  not only removes weight from the extremities, but also tightens up the face profile of the golf club head  1600  to create a unique performing golf club head  1600 . 
     In addition to illustrating this toe contour profiling,  FIG.  18    also shows a CG-B  1616  measurement relating to the shaft axis  1615  similar to the previous discussion. Once again, the CG-B  1616  measurement range is in line as the previous discussion have mentioned, and does not deviate much from the design intent of the present invention. 
       FIG.  19    of the accompanying drawings shows a cut open cross-sectional view of a golf club head  1600  in accordance with this alternative embodiment of the present invention taken along a horizontal plane. In this embodiment of the present invention, the overarching theme of placing the weights along the central portion of the golf club head  1600  reemerges again. More specifically, the golf club head  1600  further comprises of a frontal internal weight  1624  and a rear internal weight  1626 . These weights, however, different from prior embodiments of the present invention in that they can be made out of the same material as the body portion of the golf club head  1600  such as titanium and be directly cast into the body without departing from the scope and content of the present invention. These weighting members  1624  and  1626  may also be made out of a tungsten type material having a total weight of 20-23 grams to further improve the performance of the golf club head  1600  without departing from the scope and content of the present invention. 
       FIG.  20    of the accompanying drawings provides another cross-sectional cut open view of the golf club head  1600  in accordance with an alternative embodiment of the present invention taken along a vertical plane. Once again, the measurements here are very similar to the discussion previously relating to prior embodiments and the CG-Z  1612  number remain within the same range as the prior discussion. This cross-sectional cut open view of the golf club head  1600  taken along this line allows the profile and geometry of the frontal internal weight  1624  and the rear internal weight  1626  to be shown more clearly and their relationship together with the body portion of the golf club head  1600 . 
     Referring to  FIGS.  21 - 25    the golf club head  2000  has all of the mass and inertial properties discussed above. Further, the golf club head  2000  comprises frontal portion comprising a striking face  2001  having a face center FC, a crown on the upper portion of the golf club head  2000  and a sole on the bottom portion of the golf club head  2000 . The golf club head  2000  further comprises a crown return  2002  and a sole return  2003  as part of the frontal portion and a central body member  2004  that are all formed of metal. The central body member  2004  is located near the central portion of the golf club head  2000  in a heel-to-toe orientation, substantially in line along the z-axis as set forth above, and extends from the crown return  2002  and the sole return  2003  to a back edge  2005  of the golf club head. The golf club head  2000  is further comprised of a heel body member  2006  made of a non-metallic material and coupled to a heel side of the central body member  2004  and the crown return  2002  and the sole return  2003 . The golf club head  2000  also includes a toe body member  2007  made of a non-metallic material and coupled to a toe side of the central body member  2004  and the crown return  2002  and the sole return  2003 . The heel body member  2006  and the toe body member  2007  are essentially taco shell shaped, taco-shaped, in that they form a portion of the crown and a portion of the sole such that they have a c-shaped cross section. Preferably, as set forth above, the metal portions can be formed of a standard titanium materials such as TI-6-4, Ti-8-1-1, beta-titanium, and others that have a specific gravity of about 4 g/cc to 5 g/cc. 
     Alternatively, the metal portions can be formed of a standard steel materials that have a specific gravity of about 7 g/cc to 9 g/cc The heel body member  2006  and the toe body member  2007  are preferably formed of a standard composite fiber composite laminate, chopped fiber composite generally referred to as fiber-reinforced plastic (FRP), or a composite material such as those disclosed in U.S. Publication No. 2015-0360094, which is incorporated by reference in its entirety herein. Alternatively, the heel body member  2006  and the toe body member  2007  are preferably formed of structural material having a density of less than 3.0 g/cc such as a thermoplastic material such as those disclosed in U.S. application Ser. No. 16/528,210, filed on Jul. 31, 2019, which is incorporated by reference in its entirety herein, polyetherimide (PEI), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyacryletherketone (PEAK), polyetherketoneketone (PEKK) and polyvinyl chloride (PVC). The heel body member  2006  and the toe body member  2007  are preferably formed by compression molding, injection molding or 3D printing. 
     The golf club head  2000  further has a center of gravity CG that is located a distance back from the face center, CG-z, a vertical distance up from the ground plane, CG-y, a perpendicular distance from the shaft axis, GC-SA, a horizontal distance from the face center toward the heel side, CG-x and a distance back, parallel to the z-axis, from the shaft axis, CG-C. As stated above, in the current invention, the CG-z is generally between about 25 mm to about 40 mm, more preferably between about 26 mm and about 38 mm, and most preferably between about 27 mm and about 36 mm, all measured rearward from the face center FC along the z-axis shown by the coordinate system above. In addition to the CG-z numbers, an alternative measurement method is provided to measure how far back the CG is located within the club head  2000 . In this alternative method, the CG is measured from the shaft axis SA, and this measurement is illustrated as CG-C is generally measured to be between about 10 mm to about 30 mm, preferably 10 mm to 25 mm, more preferably between about 12 mm to about 28 mm, and more preferably 12 mm to 23 mm and most preferably between about 14 mm to about 21 mm, all measured rearward from the shaft axis SA along the z-axis direction shown by the coordinate system above. 
     As stated above, it is important that the strategic location of the CG rearward along the z-axis be correct, irrespective of whether it is measured from the face center FC or the shaft axis SA, for the proper functionality of the current inventive golf club head  2000 . If the CG location is too far forward, the golf club head  2000  can have a low MOI-X and MOI-Y and low backspin when contacting a golf ball. However, in the alternative, if the CG location is too far rearward, the golf club head  2000  can produce too much spin to yield desirable results. Hence, the CG location rearward along the z-axis is important for the performance of the golf club head  2000 . 
       FIG.  22    of the accompanying drawings shows another important CG measurement that is important to the proper functionality of the current invention. More specifically,  FIG.  22   , in addition to illustrating all of the components of the golf club head  2000  as previously discussed, shows another measurement of the CG location from the shaft axis SA along an x-y plane. More specifically,  FIG.  22    shows a CG measurement that is perpendicular to the shaft axis SA along this x-y plane, called CG-B for the purpose of this application. The CG-B of the golf club head  2000  may generally be between about 32 mm and about 39 mm, more preferably between about 33 mm and about 38 mm, and most preferably about 35 mm. 
     As shown in  FIG.  22   , the golf club head  2000  can further include a central support member  2010  such as wall member  2010  that is coupled to a crown portion of the central body member  2004  and a sole portion of the central body member  2004 . The wall member  2010  preferably has a thickness t that is between 0.2 mm and 5 mm, and more preferably, between about 0.4 mm and 2 mm. 
     As shown in  FIG.  23   , the central body member  2004  preferably has a heel side circumferential attachment edge  2011  and a toe side circumferential attachment edge  2012  for coupling the heel body member  2006  and the toe body member  2007 , respectively, to the central body member  2004  and the crown return  2002  and the sole return  2003 . The heel side circumferential attachment edge  2011  and the toe side circumferential attachment edge  2012  preferably extend from approximate the crown return  2002  and the sole return  2003  to a back edge  2005  of the golf club head  2000 . 
     As shown in  FIG.  24   , the golf club head  2000  can further include at least one weight member  2008  or  2009 , and more preferably, includes two weight members  2008  and  2009 . The first weight member  2008  is located on the sole portion of the club head, forward near the striking face  2001  and the second weight member  2009  is located on the sole portion of the club head, aft near the back edge  2005 . At least one of the weight members  2008  and  2009  may generally have a material density of greater than 13 g/cc, and more preferably greater than about 15 g/cc. The weight members  2008  and  2009  preferably have a mass of between about 0 grams and 50 grams, more preferably between about 3 grams and 35 grams and most preferably between 5 grams and 25 grams. In one embodiment of the invention, the first weight member  2008  has a mass of at least two times the mass of the second weight member  2009 . In another embodiment of the invention, the first weight member  2008  has a mass of less than half the mass of the second weight member  2009 . More preferably, the weight members  2008  and  2009  are interchangeable so that the CG can be adjusted forward and rearward to control the club head&#39;s launch and spin characteristics. Furthermore, the center of the first weight member  2008  is preferably located less than 30 mm from the striking face  2001  along the z-axis and the center of the second weight member  2009  is preferably located less than 20 mm from the back edge  2005  along the z-axis such that the interchangeable weights can have a maximum effect on the spin and launch characteristics of the club head. 
     In one embodiment of the present invention and as shown in  FIG.  25   , the central support member or wall member  2010  is coupled to a crown portion of the central body member  2004  and a sole portion of the central body member  2004  and extends between the first and second weight members  2008  and  2009 . The central support member  2010  preferably has a maximum height H parallel to the y-axis and a maximum depth D parallel to the z-axis. The depth D is preferably greater than the maximum height H. Also shown in  FIG.  25   , the heel side circumferential attachment edge  2011  and the toe side circumferential attachment edge  2012  for coupling the heel body member  2006  and the toe body member  2007  to the central body member  2004  can include a plurality of recesses or apertures  2013  that adhesive can enter into and better lock the components together. Alternatively, the heel side circumferential attachment edge  2011  and the toe side circumferential attachment edge  2012  may have a plurality of protrusions on the outer surface to create a gap between the heel body member  2006  and the toe body member  2007  to the central body member  2004  such that an adhesive can fill the gap and create a stronger bond therebetween. 
     In another embodiment of the present invention, the golf club head&#39;s central support member  2010  can be comprised of a plurality of strut members  2014 ,  2015 ,  2016 ,  2017 ,  2018  and  2019  that extend form the crown to the sole of the central body member  2004  between the two weight members  2008  and  2009 . Again, the central support member  2010  preferably has a maximum height H parallel to the y-axis and a maximum depth D parallel to the z-axis. The depth D is preferably greater than the maximum height H. Preferably, a first angled strut member  2014  extends from a crown portion of the central body member  2004  to the sole and a second angled strut member  2015  extends from a sole portion of the central body member  2004  to the crown, and the first and second angled strut members  2014  and  2015  preferably cross each other. Preferably, the first and second angled strut members  2014  and  2015  extend at an angle α of between 15 degrees and 75 degrees from the y-axis and an angle β of between 15 degrees and 75 degrees from the z-axis. More preferably, the first and second angled strut members  2014  and  2015  extend at an angle α of between 15 degrees and 45 degrees from the y-axis and an angle β of between 45 degrees and 75 degrees from the z-axis. The golf club head  2000  can further comprise a third angled strut member  2016  that extends from a crown portion of the central body member  2004  to the sole and a fourth angled strut member  2017  that extends from a sole portion of the central body member  2004  to the crown, and the third and fourth angled strut members cross each other. The third and fourth angled strut members also extend at angles α and β of between 15 degrees and 75 degrees from both the y-axis and the z-axis respectively. Preferably, the third angled strut member  2016  is coupled to the first angled strut member  2014  at the crown and the fourth angled strut member  2017  is coupled to the second angled strut member  2015  at the sole. Furthermore, preferably, the third angled strut member  2016  is substantially parallel to the second angled strut member  2015  and the fourth angled strut member  2017  is substantially parallel to the first angled strut member  2014 . The golf club head  2000  can further comprise a vertical strut member  2018  extending vertically, substantially parallel to the y-axis, between the first angled strut member  2014  and the second angled strut member  2015  approximate the first weight member  2008 . Even more preferably, the golf club head  2000  can further comprise a second vertical strut member  2019  extending vertically, substantially parallel to the y-axis, between the fourth angled strut member  2017  and the third angled strut member  2016  adjacent to the second weight member  2009 . 
     The advantage of the central support member  2010 , either in the form of the wall member  2010  or the angled strut members  2014 ,  2015 ,  2016  and  2017  is that it prevents the crown portion of the central body member  2004  from deflecting relative to the sole portion of the central body member  2004  in the y-axis and also prevents the portions from shearing with respect to each other in the z-axis. 
     The advantage of multiple weight members  2008  and  2009  is that the weight members can have equal mass, for example between 10 and 15 grams each, such that the CG of the club head  2000  is in a neutral position. However, the weight members  2008  and  2009  can also be comprised of a heavy weight, for example greater than 15 grams, and a light weight, for example less than 10 grams, such that the CG can be moved forward or back depending on the placement of the weights. With the heavy weight located in the aft weight member  2009 , the MOI-Y is increased and is preferably greater than about 450 kg-mm 2 . Thus, in a preferred golf club head  2000 , the MOI-Y is greater than or equal to approximately 2 times the MOI-Z. Conversely, when the heavy weight is in the forward weight member  2008 , the CG-C can be significantly decreased. For example, a preferred golf club head  2000  can have a GC-C of between 14 mm to 21 mm. 
     The advantages of the club head  2000  discussed above can also apply to fairway woods and hybrids. In those embodiments, it is understood that the numerical values for the club properties will be lower and the metal will be generally steels and high strength steels known in the art. However, the construction of the golf club head  2000  can be easily applied to these smaller heads. 
     Referring to  FIGS.  27 - 29    the golf club head  2000  has all of the mass and inertial properties discussed above. Further, the golf club head  2000  comprises frontal portion comprising a variable thickness striking face  2001  having a maximum thickness at the face center FC, a crown on the upper portion of the golf club head  2000  and a sole on the bottom portion of the golf club head  2000 . The golf club head  2000  further comprises a crown return  2002  and a sole return  2003  adjacent the striking face  2001  as discussed above and a central body member  2004  that are all formed of metal. The central body member  2004  is located near the central portion of the golf club head  2000  in a heel-to-toe orientation, substantially in line along the z-axis as set forth above, and extends from the crown return  2002  and the sole return  2003  to a back edge  2005  of the golf club head  2000 . As discussed above, the golf club head  2000  is further comprised of a heel body member  2006  made of a non-metallic material and coupled to a heel side of the central body member  2004  along the heel edge  2011  and a toe body member  2007  made of a non-metallic material is coupled to a toe side of the central body member  2004  along the toe edge  2012 . The central body member  2004  can include a plurality of protrusions  2013   a  that create an adhesive filled gap and better lock the components together. The heel body member  2006  and the toe body member  2007  are essentially taco shell shaped, taco-shaped, in that they form a portion of the crown and a portion of the sole such that they have a c-shaped cross section. Preferably, as set forth above, the metal portions can be formed of a standard titanium materials such as TI-6-4, Ti-8-1-1, beta-titanium, and others that have a specific gravity of about 4 g/cc to 5 g/cc. The heel body member  2006  and the toe body member  2007  are preferably formed of a standard composite fiber composite laminate, chopped fiber composite generally referred to as fiber-reinforced plastic (FRP), or a composite material such as those disclosed in U.S. Publication No. 2015-0360094, which is incorporated by reference in its entirety herein. Alternatively, the heel body member  2006  and the toe body member  2007  are preferably formed of a thermoplastic material such as those disclosed in U.S. application Ser. No. 16/528,210, filed on Jul. 31, 2019, which is incorporated by reference in its entirety herein, polyetherimide (PEI), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyacryletherketone (PEAK), polyetherketoneketone (PEKK) and polyvinyl chloride (PVC). The heel body member  2006  and the toe body member  2007  are preferably formed by compression molding, injection molding or 3D printing. 
     In a most preferred embodiment, the heel body member  2006  and the toe body member  2007  are preferably formed from a high crystallinity PPS, that is a PPS in which the crystallinity is greater than 40%, and more preferably, greater than about 50% as measured using differential scanning calorimetry (DSC) at a heating rate of 20° C./min. The crystallinity percentage can be calculated using the following equation: 
       % crystallinty=Δ H   sample   /ΔH   reference ×100
 
     where: ΔH sample  is the sample melting enthalpy with unknown crystallinity percentage and ΔH reference  is the sample melting enthalpy with the known crystallinity. For PPS, 76.5 J/g may be utilized as the ΔH reference . 
     In order to increase the crystallinity level in PPS, it is recommended that the material be injection molded into molds that are at a temperature of greater than 115° C. and more particularly in a mold that is between about 125° C. and 135° C. In the most preferred embodiment, the PPS crystallinity is between about 50% and 70%. The material preferably has a uniform thickness of about 0.5 mm to about 2 mm. However, in one embodiment, the toe body member  2007  has a thickness that is less than the thickness of the heel body member  2006 . In another embodiment, the toe body member  2007  and the heel body member  2006  vary such that they are thinnest on the crown portion and thicker on the sole portion. In this embodiment, the crown portions of the toe body member  2007  and the heel body member  2006  have a thickness that is preferably between about 0.5 mm and 1 mm and the sole portions of the toe body member  2007  and the heel body member  2006  are between about 1 mm and 2 mm thick. 
     The golf club head  2000  further has a center of gravity CG that is located a distance back from the face center, CG-z, a vertical distance up from the ground plane, CG-y, a perpendicular distance from the shaft axis, GC-SA, a horizontal distance from the face center toward the heel side, CG-x and a distance back, parallel to the z-axis, from the shaft axis, CG-C. As stated above, in the current invention, the CG-z is generally between about 25 mm to about 40 mm, more preferably between about 26 mm and about 38 mm, and most preferably between about 27 mm and about 36 mm, all measured rearward from the face center FC along the z-axis shown by the coordinate system above. In addition to the CG-z numbers, an alternative measurement method is provided to measure how far back the CG is located within the club head  2000 . In this alternative method, the CG is measured from the shaft axis SA, and this measurement is illustrated as CG-C is generally measured to be between about 10 mm to about 25 mm, more preferably between about 12 mm to about 23 mm, and most preferably between about 14 mm to about 21 mm, all measured rearward from the shaft axis SA along the z-axis shown by the coordinate system above. 
     As stated above, it is important that the strategic location of the CG location rearward along the z-axis be correct, irrespective of whether it is measured from the face center FC or the shaft axis SA, for the proper functionality of the current inventive golf club head  2000 . If the CG location is too far forward, the golf club head  2000  can have a low MOI-X and MOI-Y and low backspin when contacting a golf ball. However, in the alternative, if the CG location is too far rearward, the golf club head  2000  can produce too much spin to yield desirable results. Hence, the CG location rearward along the z-axis is important for the performance of the golf club head  2000 . 
     As shown in  FIGS.  29  and  31   , the weight member  2008  has less mass than weight member  2009  and is preferably made from steel (or at least a material that has a lower density that the density of weight member  2009 ). The first weight member  2008  can be located on the forward portion of the sole return  2003 , near the striking face  2001  and the second weight member  2009  located on the sole portion of the golf club head  2000 , aft near the back edge  2005 . At least one of the weight members  2008  and  2009  may generally have a material density of greater than 13 g/cc, more preferably greater than about 15 g/cc, and most preferably about 17 g/cc. Preferably, at least one of the weight members  2008  and  2009  may generally have a material density of greater than 2 g/cc and less than about 9 g/cc, and most preferably between about 4 g/cc and about 8 g/cc. The weight members  2008  and  2009  preferably have a mass of between about 0 grams and 50 grams, and more preferably between about 5 grams and 25 grams. In one embodiment of the invention, the first weight member  2008  has a mass of at least two times the mass of the second weight member  2009 . In another embodiment of the invention, the first weight member  2008  has a mass of less than half the mass of the second weight member  2009 . More preferably, the weight members  2008  and  2009  are the same shape and volume such that they are interchangeable so that the CG of the golf club head  2000  can be adjusted forward and rearward to control the club head&#39;s launch and spin characteristics. Furthermore, the center of the first weight member  2008  is preferably located less than 30 mm from the striking face  2001  along the z-axis direction and the center of the second weight member  2009  is preferably located less than 20 mm from the back edge  2005  along the z-axis direction such that the interchangeable weights can have a maximum effect on the spin and launch characteristics of the club head. More preferably, the center of the first weight member  2008  is preferably located less than 25 mm from the striking face  2001  along the z-axis direction and the center of the second weight member  2009  is preferably located less than 20 mm from the back edge  2005  along the z-axis direction. 
     As shown in  FIG.  32   , the first weight member  2008  is preferably releasably coupled to the sole return  2003  portion of the golf club head  2000  by a fastener  2020 . The first weight member  2008  may generally have a material density of greater than 4 g/cc, more preferably greater than about 7 g/cc, and most preferably between about 7 g/cc and 8 g/cc. The first weight member preferably has a light side  2021  and a heavy side  2022 . The heavy side  2022  is preferably substantially solid and as shown in  FIGS.  29  and  31    is the side identified with indicia such as with a dot. In a preferred embodiment, the first weight member  2008  has a hollow portion  2023  that forms the light side  2021  of the weight member  2008 . 
     As shown in  FIGS.  33   , the second weight member  2009  is also preferably releasably coupled to the sole portion of the central body member  2004  portion of the golf club head  2000  by a fastener  2025 . The second weight member  2009  may generally have a material density of greater than 13 g/cc, more preferably greater than about 15 g/cc, and most preferably greater than or equal to about 17 g/cc. The second weight member  2009  preferably has a light side  2026  and a heavy side  2027 . The heavy side  2027  is preferably substantially solid and as shown in  FIGS.  29  and  31    is the side identified with indicia such as with a dot. In a preferred embodiment, the weight member  2009  has a hollow portion  2028  that forms the light side  2026  of the second weight member  2009 . 
     More preferably, at least one or both of the weight members  2008  or  2009  are comprised of a light side  2021  and  2026  that includes a hollow portion  2023  and  2028  and a heavy side  2022  and  2027  that is substantially solid or is solid enough that the mass on the heavy side is greater than the mass on the light side. Alternatively, at least one or both of the weight members  2008  or  2009  are comprised of a light side  2021  and  2026  that includes a hollow portion  2023  and  2028  that can be filled with a material having a density of less than 4 g/cc and a heavy side  2022  and  2027  that is a hollow portion that is filled with a material having a density of greater than about 7 g/cc and more preferably greater than or equal to about 15 g/cc. As shown in  FIGS.  29  and  31   , the weight member  2008  has less mass than weight member  2009  and is preferably made from steel (or at least a material that has a lower density that the density of weight member  2009 ). More preferably, the first weight member  2008  has a mass of about 7 g and 14 g and the second weight member has a mass of between about 15 g and 22 g. Most preferably, the first weight member  2008  and the second weight member  2009  can be interchanged in the front and aft locations as shown in  FIGS.  29  and  31    to move the CG-C by approximately 1 mm to 5 mm and most preferably by about 2.5 mm to 3.5 mm. In the most preferred embodiment, the CG-C can be between about 14 mm and 21 mm when the first weight member  2008  is in the aft location adjacent the back edge  2005  and the CG-C can be between about 22 mm and 30 mm when the first weight member  2008  is in the forward position adjacent the striking face  2001 . Further, the first weight member  2008  and the second weight member  2009  preferably have approximately the same difference in mass between the light sides  2021  and  2026  and the heavy sides  2022  and  2027 . Preferably, the difference in mass between the light sides  2021  and  2026  and the heavy sides  2022  and  2027  is between about 4 g and 8 g. Thus, if one of the weight members has the heavy side toward the heel in the x-axis direction and the other has the heavy side toward the toe in the x-axis direction, the CG of the golf club head  2000  can be neutral in the x-axis direction as shown in  FIG.  29   . However, if the weight members have both of their heavy sides  2022  and  2027  toward the toe or the heel in in the x-axis direction, the CG can be moved away from the neutral position along the x-axis direction toward the toe or heel, respectively. Preferably, the golf club head CG can be moved at least 0.5 mm toward the toe or the heel from the neutral location and more preferably, between about 0.7 mm and 1.5 mm. As shown in  FIG.  31   , both the first weight member  2008  and the second weight member  2009  have the heavy sides  2022  and  2027  toward the toe in the x-axis direction such that the golf club head CG is moved toward the toe by about 1 mm from the neutral position GC-n. These weight members can both be rotated about the fastener such that the CG is moved toward the heel by about 1 mm from the neutral position CG-n and 2 mm from the far toe CG position as shown in  FIG.  31   . 
       FIGS.  34  through  37    show different perspective and cross-sectional views of golf club heads and their internal components that are used to achieve the performance characteristics described above.  FIG.  34    shows a perspective view of an exemplary design of a golf club head  3000  that capable of achieving the performance characteristics previously discussed with respect to the embodiments in  FIGS.  1 - 3  and  13 - 15    in particular. The golf club head  3000  is comprised of the essential components previously discussed in  FIGS.  1  and  13    in terms of a frontal portion having a striking face  3001 , a crown return  3002  and a sole return  3003  and a rear portion  3004  comprised of an aft body. In order to achieve the performance numbers above of a higher MOI-Y, a higher MOI-X, and a lower MOI-Z, a significant amount of mass is allocated towards the center of the golf club head away from the perimeter. In order to achieve this, the present invention utilizes two weighting members that are preferably comprised of high density materials that have a higher density than the frontal portion  3001 ,  3002  and  3003  and the rear portion  3004 . Preferably, as set forth above, the frontal portion  3001 ,  3002  and  3003  can be formed of a standard titanium material such as TI-6-4, Ti-8-1-1, beta-titanium, and others that have a density of about 4 g/cc to 5 g/cc. The rear portion  3004  is preferably formed of a standard composite fiber composite laminate, chopped fiber composite generally referred to as fiber-reinforced plastic (FRP), or a composite material such as those disclosed in U.S. Publication No. 2015-0360094, which is incorporated by reference in its entirety herein. Alternatively, the rear portion  3004  is preferably formed of structural material having a density of less than 3.0 g/cc such as a thermoplastic materials such as those disclosed in U.S. application Ser. No. 16/528,210, filed on Jul. 31, 2019, which is incorporated by reference in its entirety herein, polyetherimide (PEI), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyacryletherketone (PEAK), polyetherketoneketone (PEKK) and polyvinyl chloride (PVC). The rear portion  3004  is preferably formed by compression molding, injection molding or 3D printing. 
     Additionally, the golf club head  3000  includes a sole plate member  3006  secured to an outer surface of the rear portion  3004 . In a preferred embodiment, the sole plate member  3006  is also formed from standard titanium materials such as TI-6-4, Ti-8-1-1, beta-titanium, and others that have a density of about 4 g/cc to 5 g/cc. In another preferred embodiment, the sole plate member  3006  is formed from stainless steel or similar material having a density of about 7 g/cc to 8 g/cc. 
     The golf club head  3000  also includes weight members  3008  and  3009 . In a first embodiment, the weight members  3008  and  3009  can have equal mass, for example between 10 and 15 grams each, such that the CG of the club head  3000  is in a neutral position along the z-axis direction. However, the weight members  3008  and  3009  can also be comprised of a heavy weight, for example greater than 15 grams, and a light weight, for example less than 10 grams, such that the CG can be moved forward or back along the z-axis direction depending on the placement of the weights. With the heavy weight located in the aft weight member  3009 , the MOI-Y is increased and is preferably greater than about 450 kg-mm 2 . Thus, in a preferred golf club head  3000 , the MOI-Y is greater than or equal to approximately 2 times the MOI-Z. Conversely, when the heavy weight is in the forward weight member  3008 , the CG-C can be significantly decreased. For example, a preferred golf club head  3000  can have a GC-C of between 14 mm to 21 mm. 
     Referring to  FIG.  35   , the golf club head  3000  further includes an internal rib member  3010  that is located in the frontal portion. The rib member  3010  is preferably located near or at the overlapping juncture of the frontal portion and the rear portion  3004 . Preferably, the depth DD of the golf club head from the leading edge LE to the back edge  3005  is between 105 mm and 125 mm, and more preferably between about 118 mm and 122 mm. The distance of the crown return DCR from the leading edge to where the crown return  3002  abuts the rear portion  3004  is preferably about 20 mm and 35 mm and more preferably between about 30 mm and 34 mm. The distance of the sole return DSR from the leading edge to where the back end of the sole return  3003  is preferably about 24 mm and 44 mm and more preferably between about 35 mm and 42 mm. The rib member  3010  is therefore preferably located a distance from the leading edge that is between the DCR and the DSR or between 20 mm and 44 mm. Most preferably, the rib member  3010  is angled such that the distance from the leading edge to the crown portion of the rib member  3010  (at the center of the crown in the heel-to-toe direction, back from the face center) DRC is less than the distance from the leading edge to the sole portion of the rib member  3010  (at the center of the sole in the heel-to-toe direction, back from the face center) DRS. More preferably, DRC is preferably between 22 mm and 33 mm and DRS is between 26 mm and 42 mm and is at least 10% greater than DRC. Thus, the rib member  3010  forms an angle α R  that is between about 2° and 10° from the vertical plane at the DRC to a point on the sole at the DRS. The rib member  3010  has a rib height RH (the height of the rib member from the inner surface of the frontal portion) that also preferably varies from the crown center to the sole center and at the heel and toe. Most preferably, the rib height RH is between about 2 mm and 8 mm and is greatest at the sole center and shortest at the heel and toe. Most preferably, the rib member  3010  has a rib height RH of about 5 mm at the sole center, 4 mm at the crown center and is 3 mm to 3.5 mm at the heel and toe. 
     The center of the first weight member  3008  is preferably located a distance DW 1  from the leading edge LE of about 15 mm to 25 mm. The center of the second weight member  3009  is preferably located a distance DW 2  from the leading edge LE of about 80 mm to 115 mm. 
     Referring to  FIGS.  36  and  37   , the second weight member  3009  is shown in a close-up cross-sectional view. The second weight member  3009  is comprised of an internal weight member  3021  and an external weight member  3022  with a fastener  3020  coupling the members together to the rear portion  3004 . The first weight member  3008  preferably has a similar construction but would secure about the frontal portion on the sole return  3003 . Most preferably, the first weight member  3008  and the second weight member  3009  have similar shaped external weight members  3022  that can be interchanged. In this embodiment, the internal weight member  3021  and the external weight member also secure the sole plate member  3006  to the rear portion  3004  by having the rear portion  3004  and the sole plate member  3006  compressed between the internal weight member  3021  and the external weight member  3022 . In the weight embodiment shown in  FIG.  37   , the sole plate member  3006  and the internal weight member  3021  are also threaded so that they can be coupled to the rear portion  3004  before the external weight member  3022  is couple by the fastener  3020 . 
     Referring to  FIGS.  38 - 41   , another embodiment of a rear portion  4004  is shown with a pinch weight member  4009  secured near the back edge  4005  that is used to achieve the performance characteristics described above. The pinch weight member  4009  is similar to the second weight member  3009  discussed above. The pinch weight member  4009  is comprised of an internal weight member  4021  and an external weight member  4022  with a fastener  4020  coupling the members together to compress the rear portion  4004 . A first weight member, not shown, preferably has a similar construction, but would secure about a frontal portion, also not shown. In the weight embodiment shown in  FIG.  41   , the sole portion  4012  is compressed between the internal weight member  4021  and a weight retaining pocket  4023  which are also threaded so that they can be coupled to the rear portion  4004  before the external weight member  4022  is coupled to the weight retaining pocket  4023  by the fastener  4020 . The exterior surface of the weight retaining pocket  4023  is cylindrical with treads and the interior surface is preferably hexagonal or other polygon and matches the shape of the exterior weight member  4022  such that the exterior weight member  4022  cannot rotate in the weight retaining pocket  4023 . 
     In a preferred embodiment, the rear portion  4004  is formed from a crown portion  4011  and a sole portion  4012  that can be coupled by a joint connector  4013 . The crown portion  4011  and the sole portion  4012  are preferably injection molded separately and then coupled by the joint connector  4013 . The materials for the crown portion  4011  and the sole portion  4012  are preferably the same and the material for the joint connector is preferably the same or is at least compatible such that it easily joins to the crown portion  4011  and the sole portion  4012 . 
     In a most preferred embodiment, the rear portion  4004  is preferably formed from a high crystallinity PPS, that is a PPS in which the crystallinity is greater than 40%, and more preferably, greater than about 50% as measured using differential scanning calorimetry (DSC) at a heating rate of 20° C./min. In order to increase the crystallinity level in PPS, it is recommended that the material be injection molded into molds that are at a temperature of greater than 115° C. and more particularly in a mold that is between about 125° C. and 135° C. In the most preferred embodiment, the PPS crystallinity is between about 50% and 70%. Preferably, the PPS can be formed without any filler or can contain a filler such as glass filler. In the glass filler PPS embodiment, the PPS preferably has greater than about 20% glass filler, more preferably between about 20% and 50% and most preferably between about 30% and 50%. The material preferably has a uniform thickness of about 0.5 mm to about 2 mm. However, in one embodiment, the heel side  4007  has a thickness that is less than the thickness of the toe side  4006 . In another embodiment, the thickness varies such that it is thinnest on the crown portion  4011  and thicker on the sole portion  4012 . In this embodiment, the crown portion  4011  has a thickness that is preferably between about 0.5 mm and 1 mm and the sole portion  4012  thickness is between about 1 mm and 2 mm. 
       FIG.  42    shows a perspective view of golf club head that achieves the performance characteristics described above. The golf club head  5000  is capable of achieving the performance characteristics previously discussed with respect to the embodiments in  FIGS.  1 - 3 ,  13 - 15  and  34 - 36    in particular. The golf club head  5000  is comprised of the essential components previously discussed in  FIGS.  1 ,  13  and  34    in terms of a frontal portion having a striking face  5001 , a crown return  5002  and a sole return  5003  and a rear portion  5004  comprised of an aft body. In order to achieve the performance numbers above of a higher MOI-Y, a higher MOI-X, and a lower MOI-Z, a significant amount of mass is allocated towards the center of the golf club head away from the perimeter. In order to achieve this, the present invention utilizes two weighting members that are preferably comprised of high density materials that have a higher density than the frontal portion  5001 ,  5002  and  5003  and the rear portion  5004 . Preferably, as set forth above, the frontal portion  5001 ,  5002  and  5003  can be formed of a standard titanium material such as TI-6-4, Ti-8-1-1, beta-titanium, and others that have a density of about 4 g/cc to 5 g/cc. The rear portion  5004  is preferably formed of a standard composite fiber composite laminate, chopped fiber composite generally referred to as fiber-reinforced plastic (FRP), or a composite material such as those disclosed in U.S. Publication No. 2015-0360094, which is incorporated by reference in its entirety herein. Alternatively, the rear portion  5004  is preferably formed of structural material having a density of less than 3.0 g/cc such as a thermoplastic materials such as those disclosed in U.S. application Ser. No. 16/528,210, filed on Jul. 31, 2019, which is incorporated by reference in its entirety herein, polyetherimide (PEI), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyacryletherketone (PEAK), polyetherketoneketone (PEKK) and polyvinyl chloride (PVC) and composites incorporating the same. Alternatively, the rear portion  5004  is preferably formed of a standard titanium material such as TI-6-4, Ti-8-1-1, beta-titanium, and others that have a density of about 4 g/cc to 5 g/cc and is formed integrally with the crown return  5002  and the sole return  5003 . 
     In a most preferred embodiment, the rear portion  5004  is preferably formed from a high crystallinity PPS, that is a PPS in which the crystallinity is greater than 40%, and more preferably, greater than about 50% as measured using differential scanning calorimetry (DSC) at a heating rate of 20° C./min. In order to increase the crystallinity level in PPS, it is recommended that the material be injection molded into molds that are at a temperature of greater than 115° C. and more particularly in a mold that is between about 125° C. and 135° C. In the most preferred embodiment, the PPS crystallinity is between about 50% and 70%. Preferably, the PPS can be formed without any filler or can contain a filler such as glass filler. In the glass filler PPS embodiment, the PPS preferably has greater than about 20% glass filler, more preferably between about 20% and 50% and most preferably between about 30% and 50%. The material preferably has a uniform thickness of about 0.5 mm to about 2 mm. However, in one embodiment, the heel side  5007  has a thickness that is less than the thickness of the toe side  5006 . In another embodiment, the thickness varies such that it is thinnest on the crown portion  5011  and thicker on the sole portion  5012 . In this embodiment, the crown portion  5011  has a thickness that is preferably between about 0.5 mm and 1 mm and the sole portion  5012  thickness is between about 1 mm and 2 mm. 
     The rear portion  5004  is preferably formed by compression molding, injection molding or 3D printing. Additionally, the golf club head  5000  can include a sole plate member, as discussed above, secured to an outer surface of the rear portion  5004 . 
     In a preferred embodiment, the golf club head  5000  also includes weighting members  5008  and  5009 . The weighting members  5008  and  5009  can be fixed the golf club head  5000  using fasteners and/or adhesive tape such as those available from 3M. One of the weighting members  5008  is located near a central portion of said golf club head in a heel-to-toe orientation, substantially in line along the z-axis with said face center, on the sole portion  5012  and near the striking face  5001 , that is within 20 mm of the striking face  5001 . The second weighting member  5009  is located near a central portion of said golf club head in a heel-to-toe orientation, substantially in line along the z-axis with said face center, near the back edge  5005 , that is within 20 mm of the back edge  5005 . The weighting members  5008  and  5009  can have equal mass, for example between 4 and 15 grams each, such that the CG of the club head  5000  is in a neutral position along the z-axis direction. However, the weighting members  5008  and  5009  can also be comprised of a heavy weight, for example greater than 15 grams, and a light weight, for example less than 10 grams, such that the CG can be moved forward or back along the z-axis direction depending on the placement of the weights. With the heavy weight located in the aft weighting member  5009 , the MOI-Y is increased and is preferably greater than about 450 kg-mm 2 . Thus, in a preferred golf club head  5000 , the MOI-Y is greater than or equal to approximately 2 times the MOI-Z. Conversely, when the heavy weighting member is in the forward weighting member  5008 , the CG-C can be significantly decreased. For example, a preferred golf club head  5000  can have a GC-C of between 14 mm to 21 mm. 
     More preferably, at least one or both of the weighting members  5008  or  5009  are comprised of a light side  5021  and  5026  that could include a hollow portion or lighter material and a heavy side  5022  and  5027  that is substantially solid or is formed of a high specific gravity material such that the mass of the heavy side is greater than the mass on the light side. In one embodiment, the weighting members  5008  and/or  5009  are comprised of a light side  5021  and  5026  that is comprised of a material having a density of less than or equal to 4 g/cc and a heavy side  5022  and  5027  that is comprised of a material having a density of greater than about 7 g/cc and more preferably greater than or equal to about 15 g/cc. As shown in  FIG.  42   , the weighting member  5008  has less mass than weighting member  5009 , but these weights are interchangeable and can be switched. It is preferred that weighting member  5008  is formed from aluminum or thermoplastic and steel, or at least materials that have lower density than the materials of weighting member  5009 , which is preferably comprised of steel and tungsten. More preferably, the first weighting member  5008  has a mass of between about 7 g and 14 g and the second weighting member  5009  has a mass of between about 15 g and 22 g. Most preferably, the first weighting member  5008  and the second weighting member  5009  can be interchanged in the front and aft locations to move the CG-C by approximately 1 mm to 5 mm and most preferably by about 2.5 mm to 3.5 mm. In the most preferred embodiment, the CG-C can be between about 14 mm and 21 mm when the first weighting member  5008  is in the aft location adjacent the back edge  5005  and the CG-C can be between about 22 mm and 30 mm when the first weighting member  5008  is in the forward position adjacent the striking face  5001 . Further, the first weighting member  5008  and the second weighting member  5009  preferably have approximately the same difference in mass between the light sides  5021  and  5026  and the heavy sides  5022  and  5027 . Preferably, the difference in mass between the light sides  5021  and  5026  and the heavy sides  5022  and  5027  is between about 4 g and 8 g. Thus, if one of the weighting members has the heavy side toward the heel in the x-axis direction and the other has the heavy side toward the toe in the x-axis direction, the CG of the golf club head  5000  can be neutral in the x-axis direction as shown in  FIG.  42   . However, if the weighting members have both of their heavy sides  5022  and  5027  toward the toe or the heel in in the x-axis direction, the CG can be moved away from the neutral position along the x-axis direction toward the toe or heel, respectively. Preferably, the golf club head CG can be moved at least 0.4 mm toward the toe or the heel from the neutral location and more preferably, between about 0.4 mm and 1.5 mm. 
     Another aspect of the current inventions is that the weighting members  5008  or  5009  are attached to the golf club head at different angles as shown in  FIG.  43   . More particularly, the weighting member  5008  is coupled to the sole portion  5012  so that it is relatively parallel the horizontal plane when the club is in the address position. Or, in other words, the fastener  5020  for the weighting member  5008  extends substantially in the y-direction, vertically into the golf club head  5000  to secure the weighting member  5008  to the sole portion  5012 . Conversely, the weighting member  5009  in this embodiment, is coupled to the back edge  5005 , which is an aft wall that is essentially in a vertical plane, even though the aft wall is curved in the x-direction, and has a height H of between about 0.25 inches and 1 inch. Or, in other words, the fastener  5025  coupling the weighting member  5009  to the back edge  5005  extends substantially along the z-direction, horizontally into the golf club head  5000 . The angle β formed between the lines extending from the fasteners  5020  and  5025  into the club head, when viewed in the x-direction, is preferably greater than 60 degrees and more preferably between about 80 degrees and 100 degrees. 
     Referring now to  FIG.  44   , an embodiment of the invention includes the golf club head  4000 , having the inertia and CG properties discussed above, and which comprises the striking face  4001 , the crown return portion  4002  and the sole return portion  4003 , which are all preferably formed from titanium alloys and collectively form the frontal portion  4015 . The golf club head  4000  also comprises a rear portion  4004  which is preferably formed as a thermoplastic aft cup. The rear portion  4004  preferably comprises a crown portion  4011 , a sole portion  4012 , a joint connector  4013  with a weight member  4009  coupled to the back end. The weight  4009  is external and is preferably a moveable weight with reference to  FIGS.  46 - 56    discussed further below or the flip weights discussed above. 
     One manufacturing method is best understood with reference to  FIG.  45   . Thermoplastic rear portion  4004  is formed from a thermoplastic crown portion  4011  and thermoplastic sole portion  4012  which are made with continuous fibers using one or more of the thermoplastic materials discussed above. Preferably, the crown portion  4011  and/or the sole portion  4012  is formed from a multi-layer thermoplastic composite construction as set forth in co-pending U.S. application Ser. Nos. 17/205,678 and 17/225,862, which are incorporated by reference herein in their entirety. The wall thicknesses of the thermoplastic crown portion  4011  and the thermoplastic sole portion  4012  are preferably from 0.6 mm to 1.2 mm. Some designs contemplated could have essentially constant wall thickness, while designs might have walls that are thicker near the joints and any attached weight members, and thinner in other areas. The wall thickness of 0.6 mm to 1.2 mm does not include the use of foamed or honeycomb panels, which would be added to the inner surface and would be preferably considerably thicker to add stiffness. As shown, the crown portion  4011  and the sole portion  4012  are formed with no undercuts for easier manufacture. Then a joint connector  4013  is formed as a reinforcing horseshoe-shaped member such that it can reinforce the joint between the crown portion  4011  and the sole portion  4012 . 
     All three thermoplastic composite portions  4011 ,  4012  and  4013  are placed in a golf club head mold  6001  which comprises a top mold portion  6003  and a bottom mold portion  6004 . A silicon insert  6005  with an exterior shaped to match the desired interior geometry of the rear portion  4004  is placed inside the three thermoplastic composite portions  4011 ,  4012  and  4013  while they are inside the mold  6001 . This silicon insert  6005  has a pocket  6006  that is preferably pouch-shaped. Then a front mold piece  6002  is placed inside the silicon pocket  6006  to force the silicon outward against the three thermoplastic composite portions  4011 ,  4012  and  4013 , holding them in place during molding. Preferably, the front mold piece  6002  is formed from metal as well as the top mold portion  6003  and the bottom mold portion  6004 . Air is injected into the mold pocket  6006  which expands the silicon insert  6005  to apply pressure and the three thermoplastic composite portions  4011 ,  4012  and  4013  melt together at the joining surfaces while the desired shape is maintained by the mold portions  6003  and  6004  and the pressure from the silicone insert  6005 . 
     As shown in  FIG.  44   , a permanent weight member  4009  can also be attached during the final assembly mold process outlined above. The weight member  4009  could be a fourth piece added in the club head mold  6001  and can be formed from a tungsten impregnated thermoplastic, thermoplastic composite or injection molded plastic. While the weight member  4009  could be tungsten or some other metal that is simply surrounded by the thermoplastic composite portions  4011 ,  4012  and  4013  to be firmly held in place, a preferred solution is that this permanent or moveable weight member  4009  is a tungsten impregnated thermoplastic composite material or a base member formed of the thermoplastic composite matching that of the other portions  4011 ,  4012  and  4013 . Thus, in the final molding process, the weight member  4009  will not only be surrounded by the other portions  4011 ,  4012  and  4013 , but it also will be united with the surrounding portions as they melt together. It is also preferable that the joint between the crown portion  4011  and the sole portion  4012  is a butt joint. Another option is for the joint to be overlapping. The joint connector  4013  is preferably, but not necessarily, used with the overlapping joint to increase the strength of the bond. The joint connector  4013  is shown to be on the inner surface of the crown portion  4011  and the sole portion  4012 , but it could easily be located on the outer surfaces of these portions. 
     In yet another embodiment, a permanent weight member  4009  can also be attached during the final assembly mold process. Preferably, the crown portion  4011  and the sole portion  4012  are formed separately and then optionally joined in mold  6001 . Then, the crown portion  4011  and the sole portion  4012  are placed in an injection mold. Thereafter, the weight member  4009 , preferably formed from a tungsten impregnated thermoplastic, is added in the injection mold and then the joint connector  4013  is injection molded over the weight member  4009  such that the weight member  4009  is juxtaposed between the crown portion  4011  and sole portion  4012  and the joint connector  4013  and is united by the thermoplastic composite portions  4011 ,  4012  and  4013  to be firmly held in place. It is also preferable that the joint between the crown portion  4011  and the sole portion  4012  is a butt joint. Another option is for the joint to be overlapping. It is also contemplated that the crown portion  4011  and the sole portion  4012  are joined through a butt joint or overlap joint in mold  6001  and a permanent weight member or moveable weight base member  4009  is coupled to the crown portion  4011  and the sole portion  4012  through an adhesive or adhesive tape. 
     Another manufacturing method for the thermoplastic composite rear portion  4004  would be injection molding the entire rear portion  4004  as a single complete piece. Alternatively, injection molding could be used to make one or all of the several individual thermoplastic portions  4011 ,  4012  and  4013  of the final rear portion  4004 . Then these individual pieces could be joined in the mold  6001  explained above. Still further, it is contemplated that crown portion  4011  and  4012  can be molded with an overlap mold in the mold  6001  discussed above and then could be over-molded in an injection mold such that additional detail geometry is added where needed thru the over-mold injection molding process. It is also contemplated that foamed or honeycomb thermoplastic panels could be used to add stiffness and improve sound. Furthermore, a rear portion  4004  made by injection molding thermoplastic composite could use several different over-molding techniques to add the weight member  4009 . The first would be simply over-molding around a tungsten weight that is placed in the mold. The second method would be injecting the mold twice with different polymer compositions, with one of those polymers having a much higher density then the other in order to form the weight member  4009 . Preferably, the heavy polymer for the weight member  4009  would be the same polymer as the rest of the rear portion  4004 , but it is loaded with tungsten powder to reach a significantly higher density. More particularly, the weight member  4009  has a specific gravity that is between 4 and 15 times the specific gravity of the rear member  4004 . 
     In a preferred embodiment, the weight member  4009  is a moveable weight as set forth below with reference to  FIGS.  46 - 48   . 
     Referring to  FIGS.  46  and  47   , the weight member  4009  is comprised of a base member  4101  that is molded as part of or coupled to the club rear portion, as shown above, and a weighting element  4102  that is removably secured to the base member  4101 . Preferably, the base member  4101  includes an elongated channel  4103  that extends in the heel-to-toe direction along the back edge of the club rear portion. The weighting element  4102  is preferably comprised of a high specific gravity portion  4104  made of metal or tungsten filled polymer, having a specific gravity of between 5 and 15 and a mass of between 5 and 15 grams, and an elongated portion  4106 . Preferably, the elongated portion  4106  fits in the elongated channel  4103 . A first end of the elongated portion  4106  is coupled to the elongated channel  4103  by an undercut and then secured in the channel  4103 . Preferably, the elongated portion  4106  is preferably formed from PEEK, ABS or a glass filled polycarbonate. The distal end of the elongated portion is coupled to the high specific gravity portion  4104 , which also includes a mechanical fastener  4105  to releasably couple the weighting element  4102  in the channel  4103 . The elongated portion  4106  and the high specific gravity portion  4104  can also be coupled via a mechanical coupling  4107  such that different high specific gravity portions  4104  can be interchanged. 
     Referring to  FIG.  48   , another embodiment of the weight member  4009  is comprised of a base member  4201  that is molded as part of or coupled to the rear portion, as shown above, and a weighting element  4202  that is releasably secured to the base member. Preferably, the base member  4201  includes an elongated channel  4203  that extends in the heel-to-toe direction along the back edge of the club rear portion, not shown. The weighting element  4202  is preferably comprised of a high specific gravity portion  4204  made of metal or tungsten filled polymer having a specific gravity of between 5 and 15 and an elongated portion  4206 . Preferably, the elongated portion  4206  includes a plurality of flex joints  4210  and fits in the elongated channel  4203 . A first end of the elongated portion  4206  is coupled to the elongated channel  4203  by an undercut and is stretched to be secured in the channel  4203 . Preferably, the elongated portion  4206  is capable of being stretched or flexed and is preferably formed from PEEK, ABS or a glass filled polycarbonate. The distal end of the elongated portion is coupled to the high specific gravity portion  4204 , which also includes a mechanical fastener  4205  to releasably couple the weighting element  4202  in the channel  4203 . The elongated portion  4206  and the high specific gravity portion  4204  can also be coupled via the fastener  4205  such that different high specific gravity portions  4204  can be interchanged. 
     In another preferred embodiment, the weight member  5109  is an elongated weight as set forth below with reference to  FIGS.  49 - 53   . 
     Referring to  FIG.  49   , a club head  5100  has a rear portion  5104  with a weight member  5109  coupled to the rear portion  5104 . The weight member  5109  is comprised of two weighting elements  5102  that are connected by an elongated portion  5106 . Preferably, the weight member  5109  is secured into an elongated channel  5103  that extends in the heel-to-toe direction along club rear portion  5104 . The weighting elements  5102  preferably include high specific gravity portions  5105  made of metal or tungsten filled polymer, having a specific gravity of between 5 and 15 and a mass of between 5 and 15 grams, secured in apertures in the weighting elements  5102  such that different high specific gravity portions  5105  can be interchanged prior to the club&#39;s final assembly. Preferably, the elongated portion  5106  and the weighting elements  5102  are formed from a light-weight metal such as anodized aluminum or a fiber reinforced thermoplastic material such as PEEK and coupled into the channel  5103  by an adhesive or adhesive tape such as those made by 3M. 
     Referring to  FIGS.  49  and  50   , preferably, the elongated portion  5106  of the weight member  5109  has a first length L 1  and a first width W 1 . The weighting elements  5102  preferably have a second length L 2  and a second width W 2 . Preferably, the first length L 1  is at least twice as long as the second length L 2  and the second width W 2  is at least twice as wide as the first width W 1 . In the preferred embodiment the upper edges of the elongated portion  5106  and the weighting elements  5102  are all in a parallel plane. 
     Referring to  FIGS.  51 - 53   , a club head  5100  has a rear portion  5104  with a weight member  5109  coupled to the rear portion  5104 . The weight member  5109  is comprised of two weighting elements  5102  that are connected by an elongated portion  5106 . Preferably, the weight member  5109  is secured into an elongated channel  5103  that extends in the heel-to-toe direction along club rear portion  5104 . The weighting elements  5102  preferably include high specific gravity portions  5105  made of metal or tungsten filled polymer, having a specific gravity of between 5 and 15 and a mass of between 5 and 15 grams, secured in apertures in the weighting elements  5102  such that different high specific gravity portions  5105  can be interchanged prior to the club&#39;s final assembly. As shown in  FIG.  51   , a single high specific gravity portion  5105  is located in the weighting element  5102  on the toe side of the weight member  5109  such that the club head  5100  is fade biased. The high specific gravity portion  5105  could be placed into the aperture in the weighting element  5102  on the heel side to make the club head  5100  draw biased. As shown in in  FIG.  52   , similar high specific gravity portions  5105  are located in both of the weighting elements  5102  such that the club head  5100  in neutral. Referring to  FIG.  53   , a preferred embodiment of the invention includes a plurality of high specific gravity portions  5105  shown in a plurality of apertures in the weighting element  5102  on the toe side of the club head  5100  such that the club head  5100  is fade biased. If one of the high specific gravity portions  5105  is located in the heel side weighting element  5102  and the other high specific gravity portion  5105  is located in the weighting element  5102  on the toe side, the club head  5100  can be formed in the neutral position. If both high specific gravity portions  5105  are located in the heel side weighting element  5102 , the club head  5100  can be made draw biased. 
     In a preferred embodiment, the high specific gravity portion of the weight member is moveable and the weighting element is pivotally coupled to the club head as set forth below with reference to  FIGS.  54 - 56   . 
     Referring to  FIG.  54   , the club head  5200  is comprised of a weight member  5209  having a base member  5201  that is integrally molded as part of or is coupled to the club rear portion  5204  and a weighting element  5202  that is pivotally secured to the base member  5201 . Preferably, the base member  5201  includes an elongated channel  5203  that extends in the heel-to-toe direction along the back edge of the club rear portion  5204  and has a plurality of weight retaining locations  5207 . The weighting element  5202  is preferably comprised of a high specific gravity portion  5205  made of metal or tungsten filled polymer having a specific gravity of between 5 and 15 and a mass of between 5 and 15 grams. The weighting member  5209  also includes an elongated portion  5206  that retains the high specific gravity portion  5205  in one of the weight retaining locations  5207 . Preferably, the elongated portion  5206  is an elongated member that fits in the elongated channel  5203 . A first end of the elongated portion  5206  is pivotally coupled to the elongated channel  5203  by a pin or screw  5208  through an aperture  5218  and is secured to the channel  5203  by a fastener  5219  at the distal end of the elongated portion  5206 . The fastener  5219  can be released from the club head  5200  such that the elongated portion  5206  can be pivoted and the high specific gravity portion  5205  can be moved to a different weight retaining location  5207  or can be interchanged. 
     Referring to  FIGS.  55  and  56   , the club head  5300  is comprised of a weight member  5309  having a base member  5301  that is molded with or coupled to the club rear portion  5304  and a weighting element  5302  that is pivotally secured to the base member  5301 . Preferably, the base member  5301  includes an elongated channel  5303  that extends in the heel-to-toe direction along the back edge of the club rear portion  5304  and has a plurality of weight retaining locations  5307 . The weighting element  5302  is preferably comprised of at least one high specific gravity portion  5305  made of metal or tungsten filled polymer having a specific gravity of between 5 and 15 and a mass of between 5 and 15 grams. The weighting member  5309  also includes an elongated portion  5306  that retains the high specific gravity portion(s)  5305  in one of the weight retaining locations  5307 . Preferably, the elongated portion  5306  is an elongated member that fits in the elongated channel  5303 . A first end of the elongated portion  5306  is pivotally coupled to the elongated channel  5303  by a pin or screw  5308  through an aperture  5318  and is secured to the channel  5303  by a fastener  5319  at the distal end of the elongated portion  5306  such that the elongated portion  5306  is releasably retained in the elongated channel  5303 . The fastener  5319  can be released from the club head  5300  such that the elongated portion  5306  can be pivoted and the high specific gravity portion(s)  5305  can be moved to a different weight retaining location  5307  or can be interchanged. 
     Still further, it is preferable that the club heads discussed above have a peak amplitude and Critical Time similar to those discussed with reference to FIG. 11 in U.S. Pat. No. 10,245,479, which issued on Apr. 2, 2019, the entirety of which is incorporated by reference herein. 
     Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the above specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques in view of manufacturing and measuring tolerances. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements and manufacturing tolerances. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used. 
     It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.