Replaceable Lithium power supply for Blast Pack for nonstop shooting. Lightweight portability and super value. Can be recharged at any level of discharge and independant of the Blast Pack. Stable, memory free, interchangeable Lithium 4500m Ah battery modules snap in with up to 1800 full power energy reserve. With spare units, your shooting is never interrupted. Blast Pack your way through the toughest assignments!