This is a Bravo Company known as the Polymer KeyMod Rail (PKMR), model BCM-PKMR-MID-BLK.
Bravo Company's BCMGUNFIGHTER PKMR (Polymer KeyMod Rail) Mid Length is a direct replacement handguard featuring a simple drop in design. It is for AR15's with a mid-length gas system and mil-spec front sight base. With its natural ergonomics" it is slim" comfortable and lightweight. It has an aggressively textured area for enhanced traction and a reinforced KeyMod interface for durable accessory support. The aluminum heat shield reduces heat transfer to the handguard and shooters hand. Made in the USA.
Features:
Three six-hole KeyMod mounting surfaces (10:30 1:30 and 6:00);The PKMR will only fit a triangle M16 type handguard retaining cap