This is a light weight, high energy density polymer lithium battery. It outputs a nominal 3.7v at 4400mAh, including built-in protection against over voltage, over current, and minimum voltage. It comes terminated with a standard 2-pin JST connector-2.0 mm spacing between pins. Please do not attempt to charge these with anything but a specialized Lithium Polymer charger. Recommended chargers for 3.7V polymer lithium battery: Li-po Rider LiPo Rider Pro Solar Charger Shield V2 Energy Shield Features Excellent long-term self-discharge rates Robust power source under extreme conditions (-25 to 60°C) CE, Rosh, UN38.3 compliance Specifications Charge voltage: 4.2V Nominal Voltage: 3.7V Nominal capacity: 4400mAh @ 0.2C discharge Minimum rated capacity: 2100mAh @ 0.2C discharge Max. Charge current: 2.2A Max. Discharge current: 4.4A Cell weight: Approx.83g Dimension: 53mm x 51mm x 17.mm Connector type: JST2.0mm Wire length: 60±5mm Documents PL805050P 4400mAh 1S2P UN38.3 Test Report CE Test Report Verification of EMC Compliance Cargo Transportation Test Report by Air Cargo Transportation Test Report by Sea