This standard specifies the tolerances for bolts, screws and nuts with a thread diameter of 1 to 3 mm and product grade F. This standard applies to standard and non-standard fasteners for precision machinery. Note: Product grade F is generally suitable for products with high tolerance requirements.
GB/T 3103.2-1982 history
1982GB/T 3103.2-1982 Tolerances for fasteners--Bolts,screws and nuts for fine mechanics