This Standard specifies the type size, technical conditions and marks of prevailing torque type hexagon nuts (with non-metallic insert), style 2. This Standard is applicable to prevailing torque type hexagon nuts (with non-metallic insert), style 2 of which the thread specifications are M5 ~ M36, performance grades are 10 and 12, the product grades are grade A and grade B. Grade A is used for nuts of 16 mm; Grade B is used for nuts of D>16 mm.