BASTION Ridge Rear Cover Slide Back Plate for Glock - Color Compatible with Glock 17 19 21 22 23 24 26 27 29 30 31 32 33 34 35 36 37 38 39 40 41 Models Gen 1-4 ONLY. NOT COMPATIBLE WITH MODELS G42 OR G43. NOT COMPATIBLE WITH GEN 5. Hard coat anodized silver T6 machined aluminum Replaces plastic factory part Color anodized plate