For 18V lithium-ion batteries, this battery housing is for 21700 lithium-ion batteries, not 18650 batteries. The battery assembly requires the use of power cells with a discharge multiplier of 5C or higher. The voltage, internal resistance and capacity of all batteries should be the same as possible. Charge protection circuit board: overheat protection, overvoltage protection, undervoltage protection, overcurrent protection, overcharge protection. This product is a component without battery cells, used for repair and assembly of battery packs PCB color and version number change according to the actual latest inventory, PCB design may change due to changes in supply chain and processing technology. (Functionality remains unchanged) No battery cells!!! This battery housing is for 21700 -ion batteries, not 18650 batteries. This product is an assembly without a battery cell. It is used to repair and assemble battery packs that It is people who are familiar with battery performance and have practical experience in battery assembly. It can be filled with 15 21700 -ion batteries with LED battery status indicator. But this is only a shell, there is no battery inside. If using the new cores, please note that 21700 power lithium battery cells must be . A 15 cores must be equipped with resistors and capacitors to make them the same voltage. If the old battery has been repaired, test the voltage at both ends of each cell. If the voltages are different, charge each cell to the same voltage value Very Important. Before soldering the PCB, make that each battery has the same voltage. Colour:As shown Material:Metal + Plastic Package Contents: 1 set x Battery Packs Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.