Very reasonably priced Protected UltraFire 3.7V 18650 Li-ion Rechargeable Battery with IC Protection. Be safe, the ic chip will protect the battery from over charging and dis charging. Ordinary 18650 battery may explode when used in the wrong polarity or when shorted.
Package Include: 1 x Rechargeable Ultrafire 18650 4000mAh
NOTE: This battery has built in IC CHIP for charging and discharging protection. This will not charge on some branded charger. And will not work on HIGH capacity load. The built in ic chip will cut off supply voltage if the load is consuming to high current..