CAA's Thunder Vertical Forward Grip is economical with a contoured shape for comfort and a plugged storage compartment. Made of black polymer, it is compact and lightweight. The screw-down clamp locking system securely mounts to any Picatinny rail. It measures 2" L x 1.5" W, and is available in two heights - 2.75" (TVG) or 4.375" (TVG1).