This is a TROY Rail known as the BattleRail, model SRAI-SR1-12BT-00.
Troy's SOCC BattleRails with M-LOK cooling holes are narrow" sleek and provide exceptional balance and controllability. Lightweight with an ultra-low profile" snag-free design" they are ideal for close quarters maneuverability. Machined from hardened aircraft aluminum with stainless steel components and finished in Mil-Spec hardcoat anodizing" they mount to a standard barrel nut.
Features:
Lightweight
Mil-Spec Anodized
M-LOK cooling holes
Mounts to standard barrel nut
