Guntec USA Mod Lite Skeletonized M-Lok Free Floating Handguards w/Monolithic Top Rail feature a proprietary barrel nut that is included with the handguard. With M-LOK slots on 4 sides of this Guntec USA Handguard, you can add all the accessories you want, but the weight won't be there because of all the empty M-LOK slots. With a tight fit up against the receiver, the Guntec USA M-LOK Handguard w/Monolithic Top Rail slides over the barrel nut, and is locked against the receiver with 6 screws for a monolithic top rail. The handguard features triangle / diamond skeletonized cuts, making this a lightweight yet durable, free-floating forend. The handguard features a proprietary handguard nut that is necessary to install your rail; the one we provide. Specifications for Guntec USA MOD LITE Skeletonized Series AR-15 M-LOK Free Floating Handguard: Manufacturer: Guntec USA Fabric/Material: T6 Aluminum Gun Make: AR Platform Gun Model: AR-15 Gun Type: Rifle Handguard Type: Free-Float Condition: New Inner Diameter: 1.34 in Outer Diameter: 1.5 in Height: 2 in Attachment Type: Screw Quantity: 1 Features of Guntec USA MOD LITE Skeletonized Series AR-15 M-LOK Free Floating Handguard M-LOK Slots On 4 Sides of Handguard (Top, Bottom, Left & Right Sides) Tight Fit Up Against Receiver, Which Allows For A Monolithic Top Rail M-LOK Slots On Top Rail Allow For Multiple Optic / Accessory Positioning Triangle / Diamond Skeletonized Cuts Throughout Handguard to Reduce Weight Rail System Slides Over Barrel Nut And Is Locked Up Against Receiver With 6 Screws Lightest 15" Handguard In Product Line Heavy Duty Package Contents: Guntec USA MOD LITE Skeletonized Series AR-15 M-LOK Free Floating Handguard Proprietary Barrel Nut Included