Superior Quality and Brand New: 100% brand new product, manufactured with high-quality materials to ensure optimal reliability and longevity. High-Performance Insulation Material: Made from robust bakelite, offering excellent electrical insulation properties and increased resistance to daily wear and tear. Simplified Installation: Features an M12 internally threaded copper nut, allowing for quick, secure, and tool-free assembly on your equipment. Guaranteed Durability: Solid construction designed for intensive and long-term use, ideal as a reliable spare part for various machine tools. Technical Specifications: Elegant black color, 40 mm ball diameter, sold in packs of 5 to meet your maintenance needs. This product is sold by xiaosong on behalf of a third-party seller; it is a compatible product. None of the products offered in this store come with two batteries; they are powered by a single battery. Note: 1. Due to variations in lighting and screen settings, the product color may differ slightly from the images shown. 2. Please allow a measurement error of 1-3 cm due to manual measurement. 3. Please check the size before purchasing. Thank you for your understanding!