Tiger Rock .750 Low Profile Steel Gas Block with Roll Pins & Wrench -Black Black. Designed with the minimum profile to fit under nearly any quad rail system it snugly fits standard .750 diameter barrels. Features of Tiger Rock .750 Low Profile Steel Gas Block with Roll Pins & Wrench Mil-Spec dimensions .750 diameter Hardened Steel construction Non-reflective Matte Black finish Fits: AR .750" barrels Package Contents: Tiger Rock .750 Low Profile Steel Gas Block with Roll Pins & Wrench Roll Pin 2 set Screws and Allen Wrench Tiger Rock GB01-B: .750 Low Profile Steel Gas Block with Roll Pins & Wrench -Black Black