This is a Hogue Rifle Grip known as the OverMolded Rifle Grip, model 15010.
Hogue's AR-15/M16 Overmold Grip with Cargo Kit is molded from durable synthetic rubber that is not spongy or tacky" yet provides a soft recoil absorbing feel" without affecting accuracy. This modern rubber requires a completely different molding process than ordinary neoprene resulting in a much superior grip. The Hogue Cargo Management System comes with a battery cradle that can store 3 Surefire 123A" 2 AA batteries or 4 2032 batteries. An extra cover is provided that can be used in place of the battery cradle to allow storage of other items.
Features:
Batteries not included
Measures 9.5x5.5x1.5";Hogue Cargo Management System Storage Compartment;Rubber Grip;Finger Grooves