The Lock-a-Draw is for compound bows. It mounts on your bow sight, not on your bow.
Please be advised that the Lock-a-Draw requires simple assembly and tuning. It comes with 31" rod that has to be cut off for your draw length , and the trigger release is glued on with epoxy cement. Tuning involves bending the rod so that the string catch matches your anchor point when drawing the bow. This is done by paper tuning. Although the tuning instructions are enclosed with the Lock-a-Draw, they are available on this web as well at Tuning Instructions.pdf. The Compound Bow Rest & Holder also requires simple assembly. Complete instructions are enclosed with each unit. Please note that the Lock-a-Draw is not appropriate for bows that require more than 25 lbs to maintain a draw. For example, a 70 lb bow with a 65% letoff would be 70(1-0.65)= 24.5 lbs.
The ULTRAN-NOK II is recommended because it provides a specific spot to hook the string catch of your Lock-a-Draw release and it protects your bowstring from wear. It is offered as an add on because some may already have a nocking loop.
Unless you only shoot sitting down, you should also order a FOOT STIRRUP to cock the bow from a standing position.