Slim 1.5 inch outside diameter. One five slot MagPul M-Lok Polymer rail section included. Features five anti-rotation QD sling swivel sockets. Gen3 torque plate system. MIL-STD 1913 rail. Rugged construction from 6061 aluminum and hard coat anodized. Fully dehorned for a non-abrasive feel. Proprietary barrel nut and barrel nut wrench included. Some minor gunsmithing required. Not for use on gas piston guns. 100% made in the USA.