Efest IMR 18650
Efest IMR 18650 1600mAh 3.7V Rechargeable Li-Mn High Drain battery. Flat top.
Please note that due to their inherent safety IMR cells don't have a protection circuit built in. They should never be discharged below 2.5 volts or cycle life/performance will be reduced. Maximum charge voltage is 4.25 volts.