CMMG AR ZEROED Adjustable Gas Block - Black Nitride - If you're looking to shoot suppressed or just fine tune your AR to your preferred ammo, the CMMG ZEROED Adjustable Gas Block gives you the freedom to dial in the gas system exactly to your liking. A 20-position detent adjustment screw means you don't have so much gas that your gun beats itself up and you don't end up with too little gas to even cycle. The sacrificial cleanout chamber and user-serviceable design provides excess carbon a place to go where you can still clean it out. Made in the USA ; Gas blocks include a 6 inch 3/32 hex wrench to adjust gas settings and roll pin.; Specifications: Gas Block - .750 inch; Finish - Nitride; Diameter.750 inch ID; Material4140 Steel, 17-4 Stainless; TypeGas Block;