The types of bolts include connecting rod bolts, cylinder head bolts, wheel bolts, main bearing cap bolts, and other special bolts, as well as various forms of bolts with hexagonal flange faces, small square heads, projection welding, large semicircular square necks, hexagonal heads, hexagonal heads with cross recesses, and tails with tapered tips or guide pillars.

Performance level: 4.8-12.9

Flange bolt series (as shown in the right figure)