It specifies the characteristics of hexagon head bolts with metric fine pitch thread with nominal thread diameters d from 8 mm tp 64 mm, product grade A for nominal thread diameters d from 8 mm to 24 mm and nominal lengths,l, up to and including 10d or 150 mm whichever is shorter, and of product grade B for nominal thread diameters d over 24 mm or nominal lengths,l, over 10d or 150 mm, whichever is shorter.