About this item1. Product Type: High precision starlock push on locking washers2. Product Material: High quality 65Mn steel, challenging and durable3. Package Include: 7 length of M3 M4 M5 M6 M8 M10 M12 total 280pcs in a transparent box, applicable to different sizes of fasteners4. Product Feature: A Lock washing machine exerts a spring drive between the fasteners head and the substrate to create extra friction and resistance to rotation5. Application: Widely utilized in machinery equipment, business manufacturing of outrage absorption and insulation