Premium Materials: Perfect A2 standard 304 stainless steel washers with smooth surface and edge which are strong and durable, excellent corrosion resistance and rust resistance which provide long service life; Suitable for long-term outdoor work. Features: M4 washer, 100 pieces; DIN 9021, ISO 7093, inner diameter - 4.3 mm, outer diameter (OD) - 12 mm, thickness - 1.0 mm. Practical function: Effectively disperses the pressure generated by fasteners , by increasing the contact area, parts can be protected from damage and prevent loose connections between fasteners. Washers for bolts are used to reduce friction, prevent leakage, insulate, prevent loosening or pressure dispersion. Wide applications: Perfect for household and mechanical appliances, good fit for stainless steel bolts and nuts and stainless steel screws; Home repair, machine tools, furniture making, DIY, outdoor projects, craft products, equipment, etc. Precision: High precision manufacturing to make the right size washers that fit adapt well to your bindings.