Designed for quick detachable vertical grip. Internal waterproof storage compartment for up to three lithium CR123 size batteries. Mounts on Picatinny & Weaver rails. Easy installation/removal by use of internal threaded tension rod that securely positions grip in choice of locations upon rail. Batteries are secured inside waterproof battery compartment w/plug w/o-ring. Compact grip provides comfortable feel, muzzle rise & provides waterproof storage of batteries for optic or lightning systems.