Enhanced M-LOK (EM) Handguards provide a lightweight free float design for your custom AR15 build. The M-LOK system allows advanced modularity past the current 1913 picatinny rail system. Machined to mil-spec dimensions and engineered to perfection, this handguard eliminates bulk while retaining strength and stability. If you are attaching this handguard to a standard threaded upper receiver : Aero Precision handguards use the BAR interface and do not work with a standard barrel nut - you will have to use the BAR Barrel Nut. If you are using Aero Precision's M4E1 Enhanced Upper Receiver, no additional pieces are needed. Please note - This handguard is specific to the AR15/M4E1 platform. It is not compatible with the M5 .308/M5E1 platform. Features: 1 pc free float design Built in anti-rotation tabs Scalloped rails Continuous top rail 1.72" inside diameter (from barrel nut cut to forward end) fits most muzzle devices and 1.5" suppressors 1.78" inside barrel nut cut area diameter Compatible with low profile gas blocks Gen 2 Feature - Quick disconnect sling socket at the 3, 6 and 9 o'clock positions Gen 2 Feature - Additional milling along flats to aid with gripping and add visual appeal Gen 2 Feature - New profile for the continuous picatinny top rail