340 pieces in 7 sizes: 340 pieces Internal Tooth Star Lock Washer in 7 sizes: M3 x 9mm, M4 x 12mm, M5 x 12mm, M6 x 14mm, M8 x 18mm, M10 x 20 mm, M12 x 25 mm, enough to meet your usual needs. Sturdy and durable: high quality 65 manganese steel washers, black oxide coating prevents oxidation and aging, offers good corrosion resistance and high temperature performance. Excellent locking function: the lock washer exerts a spring force between the fasteners head and the substrate, creating more friction and resistance to rotation, ideal for quick repairs and carrying out repair. Wide application: widely used in machinery, furniture, electrical appliances, electronic equipment, cars, sports equipment and production industrial shock absorption and insulation. Portable tools: All star washers are stored in a transparent plastic sorting box with a specification sheet, you can quickly find what you need need, easy identification and storage.