This is a Bravo Company Vertical Foregrip known as the KeyMod, model BCM-VG-KM-MOD-3-BLK.
Bravo Company's BCMGUNFIGHTER Vertical Grip Key-Mod-Mod-3 version has a low-profile length for increased mobility and decreased snag factor. The forward angle increases the rigidity of the forearm" while providing a more natural wrist angle. It can be mounted in reverse angle to increase control when grabbing handguard and grip and its flat sides with aggressive texture give better yaw control to the shooter during firing and non-firing manipulations.
Features:
Anchor and bolt system offers a simple robust design
Lightweight 1.9 ounces
Manufactured from high quality impact resistant polymers