The Strike Industries Slide Adapter Plate (SAP) allows you to use a GEN3 slide, in conjuction with a Stike Industries Mass Driver Comp, on a GEN4 frame. Naturally a GLOCKA(R) factory or aftermarket GEN3 slide will fit and function on a GEN4 frame, but there are a few issues to address. First is the ugly gap and the second is the flex in the frame because of the large hole. Install the SAP in seconds and prevent any movement of the GEN3 recoil rod and spring from possibly damaging your GLOCKA(R) GEN4. Because there is an abundance of aftermarket GEN3 slide options, Strike Industries wants to make sure you are not restricted by fitment and have your choice to fully customize your pi Mfg: Strike Industries