340 pieces in 7 sizes: 340 pieces of internal toothed star locking washers in 7 sizes: M3 x 9 mm, M4 x 12 mm, M5 x 12 mm, M6 x 14 mm, M8 x 18 mm, M10 x 20 mm, M12 x 25 mm, enough to meet your usual needs. Sturdy and durable: High-quality 65 manganese steel washers with a black oxide coating prevent oxidation and aging, offering good corrosion resistance and high-temperature performance. Excellent locking function: The locking washer exerts a spring force between the fastener head and the substrate, creating more friction and resistance to rotation, ideal for quick repairs. Wide application: Widely used in machinery, furniture, electrical appliances, electronic equipment, automobiles, sporting goods, and industrial production for shock absorption and insulation. Portable tools: All star washers are stored in a clear plastic sorting box with a specifications sheet, allowing you to quickly find what you need for easy identification and storage.