The included proprietary barrel nut for this 15″ Free Float Hand guard fits the following Smith & Wesson M&P 15-22 models: S&W M&P15-22 Gen 1 S&W M&P15-22 Gen 2 S&W M&P15-22 Sport Performance Center S&W M&P15-22 Sport S&W M&P15-22 Pistol The barrel nut can be installed with our 15-22 Barrel Nut Wrench or 1-1/4 open end wrench. S&W M&P15-22 Free Float Hand guard Features Ultra-lightweight, heavy-duty, T6 aluminum body. Anti-rotation built into the handguard. Magpul M-LOK modular locking accessory mounting system. Top Picatinny rail at the front and rear of the handguard. Barrel nut included. Handguard slides over barrel nut and is secured against the receiver using 3 screws and a special keeper. Tumble de-burred, bead blasted, acid etched and then finished with MIL-SPEC hard coat anodizing. Length: 15″ Internal Diameter: 1.36″ Total Weight: 11 oz Recommended Tools Tacticool22 Barrel Vise Jaws Tacticool22 S&W M&P15-22 Barrel Nut Wrench 5/32 hex wrench Recommended tools for the barrel nut 1-1/4″ open end wrench Adjustable jaw wrench (AKA Crescent)