for Glock Gen 4-5 Grip Frame Slug Plug AL6 No Backstrap Black NDZ - Biohazard Engraved NDZ AL6 Billet Aluminum Grip Plug for GLOCK 17 18 19 22 23 24 25 31 32 34 35 37 - GEN4 ONLY - use WITHOUT backstrap installed 100's of High Quality Permanent Laser engraved images by NDZ Performance Fits flush, prevents snagging, debris from entering or reaching trigger assembly and firing pin Quick install and easy removal, uses spring plunger assembly for retention 100% Aluminum - NOT plastic. Also helps guide mag. into magazine well