Product Features: Material: Stainless Steel Inner Diameter: M20 Outer Diameter: 40mm Thickness: 2.5mm Color: Silver Package Content 50 x Starlock Washers Description: 1. Material: high quality stainless steel, sturdy and durable. 2. Product Type: High Precision Starlock Clasps 3. Application: widely used in equipment. Machines that produce industrial shock absorption and insulation. 4. Easy to install: sturdy and durable, high corrosion resistance for equipment and substrate, easy to install. 5. Product Features A lock washer exerts a spring force between the head of the fixings and the substrate to create more friction and rotational resistance.