Stainless steel hex nuts are used in conjunction with bolts and screws to connect and fasten parts. Among them, Type 1 six-purpose nuts are the most widely used. Grade C nuts are used in machines, equipment or structures with rough surfaces and low precision requirements. Class A and Class B nuts are used on machines, equipment or structures with smooth surfaces and high precision requirements. The thickness m of type 2 hexagonal nut is relatively thick, which is mostly used in occasions where assembly and disassembly are often required.