The AR15/M16 gas block pinning jig is used when pinning low-profile gas block and gas tube assemblies together with gas block roll pin. The AR-15 gas block pinning jig-roll pin jig works with most BCM, Rainier arms, VLTOR, Zero Hour gas blocks and others. It is made from aircraft grade 6061 anodized aluminum with a wide base for stability. Pins are driven out through the hole. can drive gas block pins in from the left or right.