No Battery Cell! This product is a component without battery core. It is intended for repairing and assembling battery packs, and is only suitable for individuals familiar with battery performance and who have practical experience in battery assembly. Lithium battery shell sleeve is compatible with 10.8V 12V BAT411, BAT420, BAT412A, BAT413A lithium batteries, and can accommodate 3 pieces of 18650 li-ion batteries. This is only a shell; there is no battery included. 1. What should be considered when assembling the pack? The 18650 power cells must have consistent model, voltage, and internal resistance. Better consistency ensures improved performance. For configuration: 10.8V uses 3 in series, 14.4V uses 4 in series, 18V uses 5 in series. The voltage detection line must be properly connected. It is recommended to use high-quality batteries instead of recycled or salvaged cells. A spot welder is required. 2. When replacing the protection board: Before replacement, measure the voltage of each group of 18650 cells to ensure they are balanced. The protection board serves only as a safety device and does not balance voltage. If the battery pack has inconsistent voltages, the battery may fail to charge or discharge properly. Replacing the protection board will not resolve imbalance issues. Use matched 18650 batteries for best results. Please note: If you do not agree with the following statements, please do not place an order: (1) PCB color may vary based on available stock. (2) PCB design may be updated while maintaining the same function and performance. (3) The number and position of components on the PCB may vary or be adjusted. Color: Black Material: Plastic The protection board color is random; specific colors cannot be requested. Battery is not included. Package Contents: 1 x BAT411 Li-ion Battery Case Only the items listed above are included. Other products are not part of this package. Note: Lighting effects and monitor settings may cause slight variation in color appearance.