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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an adjustable toilet tank flapper. More particularly, the adjustable flapper is proposed for use in most toilet tanks of the type which use 1.6 gallons of water per flush (gpf), as well as older larger sized toilet tanks using standard tank balls. 
     2. Prior Art 
     Heretofore, 1.6 gpf toilet tanks have been created by numerous manufacturers. The interior structure of each manufacturer&#39;s tank has differed in configuration to an extent where the flapper of each manufacturer has not always been interchangeable nor has there been to date a flapper which will accommodate use in 1.6 gpf tanks of most, if not all, manufacturers. 
     In this respect, the configuration of interior components of the tanks of the various manufacturers has differed in primarily two significant parameters. The first is the distance between the flush tube, to which one end of the flapper is typically anchored, and the water outlet against which the flapper seal must securely seat in water tight manner, and the second is the angle at which the water outlet is oriented relative to the horizontal. 
     Thus there has existed a need in the industry for a flapper which allows for the seal of the flapper not only to be adjustable in its distance from the anchor end of the flapper but also to be adjustable in the angulation of the seal relative to a planar base of the flapper, from which the seal depends, to assure secure and water tight seating of the seal in the water outlet of the toilet tank. 
     SUMMARY OF THE INVENTION 
     According to the invention there is provided an adjustable flapper which can be used with substantially any internalized configuration of components of toilet tanks of at least 1.6 gallon per flush capacity, the flapper comprising at least a base to which is adjustably engaged a seal assembly incorporating a seal, the seal depending from the base, and being movable in at least one desired direction relative to the base to accommodate required distancing of the seal from an anchor end of the base and required angulation of the seal relative to the base to ensure appropriate seating of the seal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective top view of the adjustable universal flapper of the present invention. 
     FIG. 2 is a blown apart perspective view of the flapper of FIG. 1 showing the individual Components thereof. 
     FIG. 3 is a perspective bottom view of a base of the flapper with a seal thereof removed to show intermediate structures of a seal assembly of the flapper more clearly. 
     FIG. 4 is a broken away view of a free end of the flapper base showing accommodation of one form of chain and float combination. 
     FIG. 5 is a broken away view of a free end of the flapper base showing accommodation of another form of chain and float combination. 
     FIG. 6 is a broken away view of a free end of the flapper base showing accommodation of a strap and float combination. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in greater detail, there is illustrated therein the adjustable universal flapper made in accordance with the teachings of the present invention and generally identified by the reference numeral  10 . 
     As illustrated, the flapper  10  includes a substantially planar base  12  having a first or anchor end  14  adapted to anchor the base  12  to a flush tube of a toilet tank (not shown), in known manner. 
     Engaged to the base  12  toward a second or free end  18  thereof is a seal assembly  19  which engages the base  12 . The seal assembly  19  includes a depending seal  20  having a planar bottom wall  22  and an outwardly and upwardly angulated peripheral wall  24 . 
     Extending upwardly from a center point of the planar bottom wall  22  is a centered hollow shaft  26 . The shaft  26  fixedly engages one end  28  of an engagement pin  30  of the seal assembly  19 . A second end  32  of the engagement pin  30  terminates in a spherical tip or end nub  34 . This spherical tip  34  is received within a cooperating cavity  36  in a slide  38  of the seal assembly  19  in a manner where the nub  34  is angularly adjustable within the cavity  36 , allowing for the bottom wall  22  of the seal  20  to be set at substantially any required angle relative to the base  12  for appropriate seating thereof. 
     The slide  38  is further adapted to be slidably engaged within a cooperating channel  40  in the base  12 , the slide  38  allowing for adjustability of the distance between the seal  20  and the anchor end  14  of the flapper  10 . 
     The second or free end  18  of the flapper  10  is configured to accommodate the most common variations of flapper chains, commonly referenced  44  Three of the most common embodiments  44   a ,  44   b , and  44   c , are illustrated in FIGS. 4-6, respectively. Two ports  45   a  and  45   b  are provided in the free end  18  for use in engaging a chain  44  thereto. Port  45   a  is configured to be rectangular and port  45   b  is configured to be circular, for assuring engageability of most chain  44  embodiments presently used, to the flapper  10 . 
     It will be understood that a float  46  made of foam rubber or the like must be engaged to the chain  44  because the bottom wall  22  of the seal  20  is flat, and therefore unable to contain an air bubble thereunder, which typically has served to float the seal  20  in prior art flappers. Thus, the float  46  replaces the function of the prior art air bubble. It will be understood that the float  46  must be secured to the chain  44  at a particular level to allow for appropriate float duration for the flapper  10  to correctly fill a toilet bowl (not shown). Thus, the float  46  is secured to the chain  44  by means of top and bottom clips  48 , as shown in FIGS. 4-6. 
     Returning to the flapper  10 , in use, it will be understood that once the relative angulation of the seal  20  to the base  12  is set to assure water tight seating of the seal  20  within a water outlet of a toilet tank (not shown), regardless of the orientation of the water outlet, a frictional clamp  50  of the seal assembly  19  cooperates with the slide  38 , the clamp  50  having a portion  77  that engages slot  40  in base  12  from an underside  51  of the base  12 , and a connector  52  of the seal assembly  19 , such as a threaded thumbscrew  52 . 
     A concurrent perusal of FIGS. 2 and 3 will best detail the seal assembly  19 . 
     It will be seen that the slide  38  incorporates a throughbore  54  in one end  55  thereof adjacent the semispherical cavity  36 . 
     It will also be seen that the frictional clamp  50  includes a threaded throughbore  56  therein, toward a first end  58  thereof. 
     A second end  60  of the frictional clamp  50  includes an undercut area  62  on an upper surface  64  thereof which mimics the shape of an undersurface  66  of the spherical tip  34  of the engagement pin  30  so that, when the clamp  50  is compressed against the undersurface  66 , the spherical tip  34  is maintained at a required angulation relative to the base  12  for proper seating. 
     Compression of the frictional clamp  50  is created by inserting the thumbscrew  52  into and through the throughbore  54  in the slide  38  and threading into and through the throughbore  56  in the clamp  50 , once the desired angulation of the tip  34  and hence the seal  20  depending therefrom is set, and once the position of the seal assembly  19 , relative to anchor end  14  of the base  12  is set. 
     Thus, it will be understood that the thumbscrew  52  accomplishes two goals simultaneously. 
     This is possible because slide  38  engages over the base  12 , while the clamp  50  engages under the base  12 , sandwiching the base  12  therebetween. 
     In this respect, it will be seen that the major portion of clamp  50  is wider than the slot  40  in the base  12  and has a portion  77  that engages in slot  40  from the underside  51  of the base  12  and that the slide  38  is not only wider than the slot  40  but includes lateral flanges  68  which engage over lateral tracks  70  on an upper surface  72  of the base  12 , to ensure alignment between the slide  38  and base  12 , with another end  74  of the slide  38  being provided with a depending cross rod retainer  76  which slides along and against the underside  51  of the base  12 , maintaining the end  74  of the slide  38  against the upper surfae  72  of the base  12 . 
     Further, as in the preferred embodiment shown, radial ribs  80  may be provided across the bottom surface  22  of the seal  20  to provide support and strength thereto. 
     As described above, the flapper  10  provides a number of advantages, some of which have been described above, and others of which are inherent in the invention. Also, modifications can be proposed to the flapper  10  without departing from the trackings herein. Accordingly, the scope of the invention is only to be limited as necessitated by the accompanying claims.

Summary:
The adjustable flapper comprises at least an adjustable flapper comprising at least a base to which is adjustably engaged a seal assembly including a seal, the seal depending from the base, and the seal assembly being movable in at least one desired direction relative to the base to accommodate any required distancing of the seal from a free end of the base and the seal being adjustable in angulation relative to the base.