BASTION Laser Engraved Mag Butt Plate, Magazine Floor Base Plate for Glock All Gen 1-5 9mm .357 .40 .45 Gap - Tactical Surface Compatible with Glock Models 9mm 40cal, .357, 45 GAP ONLY GEN 1-4. NOT COMPATIBLE WITH GEN 5 Hard coat anodized black T6 machined aluminum HARD COAT ANODIZED FINISH GROOVES ON BOTH SIDES AND THE FRONT FOR POSITIVE FINGER PURCHASE DIMPLES FOR MARKING OF MAGAZINES