This high quality 3.7V Li-Ion rechargeable battery from Tenergy is made from a single 2200mAh cylindrical 18650 cell with PCB protection. It is lightweight and has a higher energy density than most rechargeable batteries. It has no memory effect, a low self discharge rate, and lasts longer than a NiMH battery. A built-in IC chip prevents the battery pack from over-charging, prolonging your battery life.