1.material:carbon steel 2.size:M3-M6 3.nickel plated 4.OEM is welcome 5.certificate:ISO9001 , ISO14001 1. Material: iron, steel, carbon steel.2. surface treatment: nickel/zinc plated , black oxide.3.Delivery time: according to your request.4.we can make as your design and drawing.5. Payment: L/C or 30% in deposit, 70% against B/L COPY.6. we can supply SGS certification. flat washer