GEN 4 ADAPTERS FIT STANDARD & COMPACT GLOCK GEN 4 SF FRAMES MODELS: 17, 19, 21, 22, 23, 34, 35 The GEN 4 GRIP FORCE ADAPTER was specifically developed to fit GLOCK's GEN 4 pistol in its base "short frame" configuration. The short frame configuration does not utilize either the Medium or Large factory grip panel on the frame. The GEN 4 GRIP FORCE ADAPTER eliminates the drawbacks associated with permanent modifications to your factory pistol. The GRIP FORCE GEN 4 ADAPTER mates completely to the back strap of the GEN 4 frame, permitting the shooter's hand to conform to the frame in a more secure manner. This offers more control and allows the shooter to index the pistol on target more efficiently.