[Battery Type] Support 18650/21700 rechargeable batteries, unlike other only support 18650 batteries. No welding, directly installed on the battery can be used. (Shipments do not include batteries, only the material shell)、[Applicable to multiple scenarios] Outdoor travel/outdoor emergency/home/school use etc. ..... Compact size easy to carry does not take up space.

Battery positive and negative poles can not be reversed, reverse will burn board scrapped, placed a good battery after the first use, function test can be used normally, and then close the shell, the shell can not be disassembled twice, assembled inside the available sponge double sided tape will be fixed battery.