The AR15/M16 gas block pinning jig is used when pinning low-profile gas block and gas tube assemblies together with roll pin. The AR-15 gas block pinning jig works with most BCM, Rainier arms, VLTOR, Zero Hour gas blocks and others. Made from aircraft grade 6061 Anodized Aluminum with a wide base for stability. Through hole to drive pins out. Can drive gas block pins in from left or right.