This is a Magpul Industries Handguard known as the MOE M-LOK, model MAG427-GRY.
The Magpul MOE M-LOK Hand Guard (Magpul Original Equipment) for AR15/M16 rifles with rifle-length gas systems combines the light weight of a standard hand guard with modular flexibility. Designed with versatility in mind" M-LOK slots at the two" six" and ten o'clock positions allow the attachment of optional 1913 Picatinny rail sections and other M-LOK accessories for the direct mounting of tactical lights" slings" grips" etc. Reinforced" heat-resistant polymer construction provides operational durability without the weight and expense of an aluminum rail hand guard. Front extensions and lower lip provides additional operator protection from hot front sight assembly.
Features:
Replaces standard M16-type rifle-length hand guards
M-LOK slots at the two, six, and ten o'clock positions
Reinforced, heat-resistant polymer