Designed for M4, M16 and AR-15 firearms, this grip can store 2 AA or 123 lithium batteries. The cavity is water-resistant and virtually indestructible. It's also been ergonomically designed to provide hours of comfort in combat. BattleGrip includes anti-rattle battery spacers, stainless steel Dry-Lok fastener and installation tool. Available in 3 different colors.