High quality carbon steel.It has good machinability and high toughness up to a temperature of about 800 degree. They have rust resistance and excellent oxidation resistance in harsh environment such as high temperature, cold temperature and high humidity area, which can guarantee for a long time. Various screw sizes: M2 * 4 - M2 * 20, M3 * 4 - M3 * 30, M4 * 6 - M4 * 30 to meet different needs, it is a very important hand tool for family. With M2, M3 and M4 nuts and washers, installations are now more precise and the contact area is enlarged, which reduces pressure and protects parts and screws. The nuts and washers are arranged in a storage box, with which you can easily find yourself in the series and avoid losing them if necessary. They are antioxidants and corrosive even at high temperatures. The main use of stainless steel hexagon screw is very common in electronics, electrical appliances, chemicals, water, machinery and equipment, furniture and many other fields. Material Carbon