This standard specifies the type 2 hexagonal 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. If other technical requirements are required, they should be selected from current standards (such as GB/T 196, GB/T 3098.4, GB/T 3098.10 and GB/T 3103.1). Coarse tooth nuts specified in GB/T 6175 should be preferred. Note: For l-shaped hexagonal nuts with fine teeth, see GB/T6171.