ISO 8676:2011 specifies the characteristics of hexagon head screws with metric fine pitch thread with nominal thread diameters, d, from 8 mm to 64 mm, of 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 the 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 the shorter.