This standard specifies the type 2 all-metal hexagonal lock nuts with thread specifications M8X1~M36X3, fine thread, performance grades 8, 10 and 12, and product grades A and B. Grade A is used for D<=16 mm; Grade B is used for nuts with D>16 mm. Note: This kind of nut is equivalent to the GB/T 6176 nut except for the dimensions m and h. If other technical requirements are required, they should be selected from current standards (such as GB/T 196, GB/T 3098.9 and GB/T 3103.1).