Fasteners, commonly known as screw nuts, are mechanical basic parts, known as "the rice of industry", from the space shuttle, automobile and mechanical equipment, to the small desk and chair bench, all have its shape. This industry belongs to the strategic industries of labor - intensive, capital - intensive and high - tech. After years of development, China has grown into the world's largest producer of fasteners. It is reported that at present, there are nearly 10,000 fastener manufacturing and trading enterprises in China, with more than one million employees, contributing a high degree of employment. Carbon steel fasteners produced in China are mainly used in automobile industry, electronic products, electronic equipment, mechanical equipment, construction and general industrial applications.