This is a Pearce Grip Frame Insert, model PGGFI.
This unit installs in the bottom rear cavity of the frame utilizing the lanyard hole for retention. Fits M17" 18" 19" 20" 21" 22" 23" 24" 31" 32" 34" 35" 37" and 38. This product will not fit any SF (Short Frame) or any Generation 4 or 5 frames.
Features:
High Impact Polymer
Keeps Out Dust and Debris
Uses Lanyard Hole For Retention