18500 3.2V 1000mah 4-Pack Long Lasting Rechargeable Battery  3.2V 18500 size Cylindrical Li-Ion Cell Lighter weight and higher energy density than any other rechargeable cell 18500 cell is a little shorter than the 18650 cell, and it is perfect for building compact sizedpacks and high capacity packs for RC aircraft, RC cars, or camera battery. Flashlight Batteries