The Wilson Combat Lo-Profile Gas Block is a rugged, securely mounted gas block that will vastly improve your AR-15's reliability. This low-profile gas block will fit underneath all popular free-floating rail systems, but heavy enough to evenly dissipate heat and resist gas leakage even in high round count use. 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. Precision bored to .750 inches and perfect for your Wilson AR barrel or the barrel of your choice. Secures to barrel with provided hardened set screws. 0.75 inches Diameter Hardened Chromoly Steel Corrosion Resistant Phosphate Finish 0.950 inches Length Includes Set Screws & Gas Tube Roll Pin