The Geissele Super Gas Block is a low profile gas block, designed to fit under most free floating handguards. Precision investment cast from 17-4 precipitation hardening stainless steel, the gas block provides corrosion resistance and strength to withstand thousands of rounds and never let you down. The included instructions cover the standard set screw installation method, as well as Geissele's own "Bombproof Installation". The bombproof installation uses an included coil pin to lock the gas block in place on the barrel so that it will never slide or twist under any operating conditions. Additionally the Super Gas Block comes with a SS dowel pin that can be used to effortlessly line up the SGB to Geissele CHF barrels to ensure a perfect alignment with the gas port. Included: Bombproof Coil Pin, 2 set screws, Gas tube coil pin, Stainless steel barrel alignment pin