This high quality 3.7V Li-Ion rechargeable battery pack is made from 3 x 2200 mAh cylindrical 18650 cells with PCB and a poly switch for maximum protection. It is light weight and has a higher energy density than most rechargeable batteries, has no memory effect, and has a longer storage life than NiMH batteries. Simply connect your Li-Ion battery pack with two or three other PCB ready battery modules in parallel and presto, you have yourself your own individualized battery pack! A Built-in IC chip prevents the battery pack from overcharging and over discharging, prolonging your battery life.