Item Type: Starlock Washers Product Model(inner diameter x outer diameter): M3x9mm; M4x12mm; M5x12mm; M6x14mm; M8x18mm; M10x20mm; M12x25mm Material: Carbon steel Package List 120 x M3 Washer 120 x M4 Washer 120 x M5 Washer 100 x M6 Washer 100 x M8 Washer 80 x M10 Washer 40 x M12 Washer 1[MULTIPLE SIZES] There are 7 most common sizes, M3, M4, M5, M6, M8, M10, M12, to meet your daily needs, useful and practical 2[LOCKING EFFECT] The lock washer exerts a spring force between the machine head and the bottom plate, and fixes the hard washer on the hard bolt thread on the front of the bottom plate to increase friction and rotation resistance 3[WIDE APPLICATION] Widely used in mechanical equipment, electronic equipment, household appliances and other fields, suitable for craftsmen, professionals, industries, craftsmen and decoration 4[GOOD QUALITY CARBON STEEL] Adopt good quality carbon steel material, with higher hardness and better wear resistance 5[EASY ORGANIZATION] Each size is separated in a storage box for easy access and storage, more convenient for you to use