King Arms PEQ Battery Case with 11.1V 1300mAh 12C Lithium Battery (KA-BAT-19). It is also compatible with 1400mAh 9.6V / 10.8V battery for battery box. PEQ box mounts to any standard 20mm accessory rail.

*Note:  This product INCLUDES a Lithium-Polymer (Li-Po) battery pack.  ONLY use Li-Po rated battery chargers to charge this battery, otherwise permanent damage to the battery WILL occur.  Also be aware of Li-Po charghing and discharging prior to use to avoid damage to battery or to potential battery fire.