Magpul M-LOK Thumb Shelf

The M-LOK Thumb Shelf gives your support hand thumb a hard reference point on the handguard. It drops into a single M-LOK slot on an octagonal aluminum handguard and becomes a repeatable index every time you build your grip. The ribbed, curved top gives the thumb something to push against, which helps hold the muzzle down through recoil and steadies the rifle when you are braced against a barrier.

The shelf is ambidextrous, so it works the same for left hand and right hand shooters, and it only uses one slot of rail space. Magpul molds it from their own reinforced polymer, so it adds almost no weight to the front end. Note that it is built for octagonal aluminum handguards, not polymer or round profile forends.