The NiteCore  NL189 3400mAh 18650 rechargeable li-ion battery has built in IC  protection that will protect against damage due to both low and high  voltage. These batteries are designed to perform under high discharge  applications. You may charge these batteries over and over for years to  come with a rating of more than 500 charge-discharge cycles. This is a  button top cell making it easier to use with many flashlights.  Rechargeables offer a great value over standard primary batteries.  3400mAh 3.7V 12.6Wh. 3400mAh 3.7V 18650 Li-ion Rechargeable NL189 Batteries Integrated overcharge & discharge protection circuits 500 charge cycles Certified by CE， UL & ROHS Voltage: 3.7V Electricity: 12.6Wh Charging Current: Maximum 2A. (1A Current recommended) Weight: 45.5g Integrated battery overcharge/discharge protection circuits Charging Cycle count: More than 500 charge/discharge cycles Equipped with nickel-plated S.S protector at each end to ensure high impact resistance， good electrical conductivity and oxidation resistance.