Mini Butterball 2Pcs 3.7V 18650 4000mA Battery Protected Rechargeable Lithium Battery with 18650 charger 3.7V 18650 4000mA Rechargeable Lithium battery. No memory effect, can be recharged up to 700 times when fully.Safe and environment. With overcharge / discharge protection function that you can use it without worry. This 18650 battery is compatible with various kind of flashlight and LED headlamps, bike lights, etc. High energy density, long life battery.