This is a Bastion Slide Back Plate known as the Pirate Sword, model BASGL-SLD-BW-PIRATE.
Bastion slide back plates are machined from the highest quality T6 aluminum using the highest tolerances to give you the exact fit you require" then hard coat anodized black and laser engraved for extreme durability!
Features:
Laser Engraved
T6 Aluminum
Hard Coat Anodized
Glock models 17-41 GEN 1-4 ONLY