Features: Designed exclusively for 18V tools, this high capacity battery shell assembly set securely houses 15x21700cells with built in PCB protections against overcharge, discharge, and short circuits. Featuring impacts resistant ABS construction and complete components including metal connectors, this 15cell battery housing ensures safe power delivery while maintaining tool balance through lightweight engineering. Ideal for professional contractors, power tool enthusiasts, and DIYers requiring reliability extended use for 18V equipment. Need semi-manufactured product Advance notification(Very Important): Please read carefully! To use this product, you need to have some professional knowledge and experience. We do not ensures that you can use it well. You must have 15pieces of 21700 libatteries and the tools such as spots welding machines, soldering irons, multimeters, and suitable chargers, Specifications: Component: ABS, PCB, metal Size:Approx.13.5x9x10cm Color: black Suitable for enthusiasts to create customized power tools or equipment to meet specific needs and enhances creativity. For 18V LiBattery Applicable battery: 15x21700 lithium batteries (this product does not include batteries) Applicable scenario:Handmade projects,Repair and rebuild power tools, Package Includes: 1Set Battery Case(Battery not included) note: Please allow 1-3cm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color.