This standard specifies the type 2 hex nuts with thread specifications M5~M36, performance grades 9 and 12, and product grades A and B. Grade A is used for D<=16mm; Grade B is used for nuts with D>16mm. If other technical requirements are required, they should be selected from current standards (such as GB/T 196, GB/T 3098.2 and GB/T 3103.1). Note: See GB/T 6170 for Type 1 hex nuts.