It can hold 15 pieces of 21700 li-ion batteries. This is only a shell; no battery is included inside. Compatible with 20V and FlexVolt 60V Lithium Battery systems. Designed for battery repair and assembly, intended only for individuals familiar with battery performance and experienced in battery pack assembly. Non-original, , no battery cells included. Advance notification (Very Important): 1. Color: Blue, Green, Red, or other random colors. PCB color and version may vary based on current inventory. 2. PCB design may change due to supply chain or manufacturing updates. Note: After assembling the battery pack with this protection board, if there is no voltage output upon initial power-up, activate it using a dedicated charger. Precautions for use and assembly: 1) When welding battery leads or sampling points, ensure correct polarity. Incorrect connections may damage the circuit board, which must be retested before reuse. 2) During assembly, avoid direct contact between the circuit board and battery cell terminals to prevent damage. Ensure secure and reliable installation. 3) Use grounded welding equipment and observe electrostatic discharge (ESD) protection to prevent damage from electric leakage or static. 4) Avoid touching components on the circuit board with wires, soldering irons, or tools during use to prevent short circuits or component damage. 5) Take precautions against static, moisture, and water exposure during use. Note: Variations in screen printing may occur due to different production batches; this does not affect functionality. Color: Random (cannot specify color) Material: PCB + Plastic Package Contents: 1 x Battery Protection Board Only the items listed above are included; all other accessories are not included. Note: Lighting effects and display settings may cause slight color differences between the image and the actual item. Measurement error allowed within +/- 1-3 cm.