Behold, the tried and true handguard design that comes standard on all GGP MKII rifles is available for the builders out there. GGP AR-10 handguards are extruded from 6061-T6 Aircraft Grade Aluminum, finished with True Black Type III Class 2 Hard Coat Anodizing and are available in 15" and 18" lengths. The inside diameter is 1.380" and uses a non-proprietary barrel nut that does not require timing. Simply tighten the barrel nut to 65 ft lbs, slide the handguard over until it is flush with upper receiver. Left and Right side index tabs ensure the handguard does not twist under use. Lastly use the two provided fastening screws to tighten the handguard around the barrel nut, at an approximate torque spec of 35 in lbs.Features :6061-T6 Aircraft Grade Aluminum ExtrusionFull Length picatinny top rail with engraved numerical T-markingsNon-Proprietary Barrel Nut and two fastening screwsLOK attachment slots at 3, 6 and 9 oclock positionsForward MLOK slots at 1 and 11 oclock positionsCompatible with all forged upper receivers and most billet upper receiversDoes not include wrench, barrel nut compatible with standard armorers wrench