US Made M-LOK Slots On 3 Sides Of Handguard (Bottom, Left & Right Sides) Rail Slides Over Barrel Nut, And Is Compressed Down Against Receiver With 4 Screws Heavy Duty Anodized Black Finish T6 Aluminum Body Proprietary Barrel Nut Included Tight Fit Up Against Receiver, Which Allows For A Monolithic Picatinny Top Rail Internal Diameter: 1.32″ 16.5″ Length AIR-LOK Series – Compression Lock Down Design Total Weight Including Barrel Nut Is 13.7 oz Machined QD Swivel Socket On Rear End Of Handguard (Right & Left Side) Triangle / Diamond Skeletonized Cuts Throughout Handguard To Reduce Weight