General description This 10 Hole 21700 Li-Ion Battery Plastic Case with PCB Protection Board is designed for assembling and repairing battery packs, specifically compatible with Zhipu Hongsong Jingmi 18V Lithium Batteries. Please note that this product is a shell only and does not include batteries. Technical specifications Capacity: Holds 10 pieces of 21700 li-ion batteries Material: Plastic Color: Random (Blue, Green, Red, etc.) PCB Specifications: Built-in IC detects cell voltage current Protection Features: Overheat, overvoltage, undervoltage, overcurrent, and overcharge protection Measurement allowed error: +/- 1-3cm Installation Ensure all battery cells have the same voltage before welding the PCB. If using new battery cores, ensure they are equipped with resistance and capacitance for voltage consistency. For old batteries, test the voltage of each cell and charge them to the same voltage if necessary. Usage This product is intended for individuals familiar with battery