The SLR Rifleworks SD ZRO AR-15 M-LOK Suppressor Handguard is designed to allow a normally sized suppressor to slide inside the handguard to thread onto the barrel. This provides a very modern, clean look. FeaturesIncludes 4 special locking nuts for accessories on suppressor end to mount without interference with suppressor. (Up to 1.7" OD Suppressors)2 Limited Rotation QD'sNo timing of barrel nut required, no shims needed7075 Barrel nut included w/Hardcoat AnodizeFree Floating DesignProven Slip fit locking mounting system and universal anti rotation insertBarrel nut uses standard wrenches or SLR Billet wrench for perfect fitContinuous top rail design allows optic mounts to cross receiver/handguard threshold