Duralite Receiver 4600mAh 2S2P 6.6V Lithium Phosphate (A123) Redundant Battery Pack with built-in Balancing Safety Circuitry, Rx Lead with Universal Connector and (2) 16 gauge High Power Leads with EC3 Connectors for Spektrum AR9100 receiver. Specifications: Dimensions: 3" x 2 1/4" x 2" (76mm x 57mm x 50mm) Weight: 11.6 oz. (330g) Voltage/Capacity: 6.6V/4600mAh Configuration: 2 cells in Series, 2 cells in Parallel Charge only with Li-Phosphate Charger!!!! No Voltage Regulator necessary, plug directly to Rx!!!!