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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND 
       [0001]    Current stab couplers rely on additional tooling to allow a remotely operated vehicle (ROV) to externally mate the stab coupler connectors. The connectors are typically housed in junction plates which may need to be deployed via downline. 
     
    
     
       FIGURES 
         [0002]    Various figures are included herein which illustrate aspects of embodiments of the disclosed inventions. 
           [0003]      FIG. 1  is a cutaway view in partial perspective of an exemplary receptacle according to an embodiment of the invention; 
           [0004]      FIG. 2  is an end view in partial perspective of an exemplary receptacle according to an embodiment of the invention; 
           [0005]      FIG. 3  is a cutaway view in partial perspective of an exemplary stab according to an embodiment of the invention; 
           [0006]      FIG. 4  illustrates an exemplary stab entering into an exemplary receptacle; 
           [0007]      FIG. 5  illustrates the exemplary stab, which has entered into the exemplary receptacle, with its grab sleeve collets engaged; 
           [0008]      FIG. 6  illustrates an exemplary stab which has entered into the exemplary receptacle being actuated by a remotely operated vehicle; and 
           [0009]      FIG. 7  illustrates the exemplary stab which is fully engaged. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0010]    Referring to  FIGS. 1 and 2  single line stab coupler  1  comprises receptacle  10  and stab  20 . 
         [0011]    In a first embodiment, receptacle  10  is substantially tubular and comprises receptacle housing  19 , back plate  18  disposed proximate connector end  16 , and one or more hydraulic couplers  11  disposed proximate connector end  16 . Hydraulic couplers  11  typically are one-half inch couplers but may be of any appropriate size. 
         [0012]    Receptacle housing  12  comprises receiving end  15  and connector end  16  disposed opposite receiving end  15 . 
         [0013]    Receiving end  15  comprises open end  19 , typically conically shaped, which comprises mating slot  14  through a portion of receptacle housing  12 . Mating slot  14  defines key receiver  18  ( FIG. 2 ) configured to cooperatively receive alignment key  32  ( FIG. 3 ) when stab  20  ( FIG. 2 ) is inserted a predetermined distance into receptacle  10 . In certain embodiments, mating slot  14  extends through receptacle housing  12  to open end  19 . As illustrated in  FIG. 1 , however, mating slot  14  need not extend all the way to open end  19 . 
         [0014]    In preferred embodiments, connector end  16  is configured to connect to subsea equipment. 
         [0015]    Back plate  13  further comprises one or more collet receivers  17  configured to receive a complimentary set of grab sleeve collets  33  ( FIG. 3 ), where each grab sleeve collet  33  may be configured to compress and then conform to a respective complimentary collet receiver  17 . Back plate  13  is typically bolted. 
         [0016]    One or more hydraulic couplers  11  is typically configured to be received at least partially into and through back plate  13 . In certain embodiments, each of the ends of hydraulic couplers  11  comprises a medium pressure union fitting configured to be connected to a high collapse resistant (HCR) hose for stabs  20  ( FIG. 3 ). 
         [0017]    Referring now to  FIG. 3 , stab  20  comprises stab housing  34  which further comprises stab end  37  and handle end  38 . Stab housing  34  is configured to be received into open end  19  of receptacle  10 . Stab housing  34  is typically substantially tubular and defines interior void  36  at least partially therethrough. Alignment key  32  is disposed about a predetermined portion of stab housing  34 , typically at least partially disposed about an outside portion of stab housing  34 . One or more grab sleeve collets  33  is disposed within interior void  36  proximate stab end  37 . Sleeve guide  39  is disposed within interior void  36  intermediate stab end  37  and handle end  38 . 
         [0018]    Locking rod  30  is slidingly disposed within interior void  36  and extends through grab sleeve collet  33  and sleeve guide  39 . Locking rod  30  may further comprise boss  30   a  configured to prevent grab sleeve collet  33  from over deforming. In certain embodiments, locking rod  30  is threaded. 
         [0019]    In certain embodiments, spring  31  is disposed about locking rod  30  intermediate handle end  38  and sleeve guide  39  and configured to keep grab sleeve collet  33  engaged. Spring  33  is configured to provide pre-load tension such that as locking rod  30  progresses within interior void  36  and/or rotates it expands grab sleeve collet  33  first. 
         [0020]    Handle  40  may also be present and attached to locking rod  30 . Where handle  40  is present, it typically comprises threaded locking rod  42  and locking rod  30  further comprises handle attachment end  41  configured to attach to handle connector  42 , typically pivotally. Handle  40  may be configured to be maneuvered by remotely operated vehicle (ROV)  100 . 
         [0021]    In the operation of exemplary embodiments, referring generally to  FIGS. 4-8 , stab insertion may be accomplished positioning stab  20  proximate receiving end  15  of substantially tubular receptacle  10 . Receiver  10  may be connected to a predetermined piece of subsea equipment with metal tubing or with one or more HCR hoses, by way of example and not limitation including subsea trees, manifolds, and the like. 
         [0022]    Stab  20  is then mated into substantially tubular receptacle  10  by inserting a stab end  37  of a substantially tubular stab housing  34  of the stab  20  into the receiving end  15  of the substantially tubular receptacle  10  and aligning alignment key  32  disposed about a predetermined portion of the substantially tubular stab housing  34  with key receiver  17  configured to cooperatively receive the alignment key  32  when the stab  20  is inserted a predetermined distance into the substantially tubular receptacle  10 . 
         [0023]    Grab sleeve collet  33  disposed within the interior void proximate the stab end is then allowed to compress and conform to a corresponding feature of substantially tubular receptacle  10  as stab  20  is inserted into the substantially tubular receptacle  10 . 
         [0024]    Threaded locking rod  30 , slidingly disposed within interior void  36  and extending through grab sleeve collet  33  and sleeve guide  39 , is pulled back by rotating handle  40  connected to locking rod  30 . Pulling locking rod  30  back may further comprise pulling locking rod  30  into grab sleeve collet  33  and temporarily locking pulling rod  30  in place. 
         [0025]    Stab  20  and receiver  10  are mated by continuing the rotation of locking rod  30  to advance stab  20  into receiver  10 . Advancing stab housing  34  of stab  20  into receiver  10  may allow stab housing  34  to act as a nut on locking rod  30  in view of back plate  18  comprising inner diameter threads. 
         [0026]    The foregoing disclosure and description of the inventions are illustrative and explanatory. Various changes in the size, shape, and materials, as well as in the details of the illustrative construction and/or an illustrative method may be made without departing from the spirit of the invention.

Summary:
A single line stab uses internal threading that allows a remotely operated vehicle (ROV) to mechanically mate up the stab and receptacle without the use of additional tooling. The use of a single coupler allows for a compact stab instead of the large junction plates that are currently used. Can be used to hydraulically control valves, inject fluid, or to sample fluids sub sea.