1. It is made of manganese steel and has a long service life. 2. Easy to use, all gaskets will be packed in a strong transparent plastic box for easy access. 3. Scope of application: Widely used for shock absorption and insulation in machinery, furniture, electrical appliances, electronic equipment, automobiles, sports equipment, and industrial production. 4. Function: The lock washer exerts an elastic force between the head of the fastener and the base material to generate greater friction and rotation resistance. 5. Surface treatment: black anodized 6. Material: 65 manganese steel 7. Product specifications: M3 x 9MM: inner diameter 3mm outer diameter: 9mm M4 x 12MM: inner diameter 4mm outer diameter: 12mm M5 x 12MM: inner diameter 5mm outer diameter: 12mm M6 x 14MM: inner diameter 6mm outer diameter: 14mm M8 x 18MM: inner diameter 8mm outer diameter: 18mm M10 x 20MM: inner diameter 10mm outer diameter: 20mm M12 x 25MM: inner diameter 12mm outer diameter: 25mm 8. Product composition: M3 x 40 PCS M4 x 30 PCS M5 x 30 PCS M6 x 30 PCS M8 x 30 PCS M10 x 20 PCS M12 x 20 PCS