Wilson Combat's Lo-Profile Gas Block will fit underneath all popular free-floating rail systems, but is heavy enough to evenly dissipate heat and resist gas leakage. Precisely machined from hardened chromoly steel with a dark, corrosion-resistant phosphate finish, this is the ideal gas block for a professional or amateur custom AR build. It is precision bored to .750 and includes the gas tube roll pin, for a length of .950. It also includes hardened set screws to secure it to your barrel.