This is a Bravo Company Vertical Foregrip known as the KeyMod, model BCM-VG-S-KM-BLK.
Bravo Company's BCM Gunfighter's Vertical Grip (Short) KeyMod version has a low-profile length for increased mobility and decreases "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 your control when grabbing the handguard and grip. The flat sides give better yaw control to the shooter during firing and non-firing manipulations and has an aggressive texture with storage inside the grip. It requires three KeyMod attachment hole mounting points. It is made in the USA and manufactured from high quality" impact resistant polymers.
Features:
Quick detachable Tool-less Direct Mount KeyModâ„¢ interface
Requires three KeyModâ„¢ attachment hole mounting points
Spring-loaded clamps