DIN 931-2
DIN 931-2 Hexagon head bolts - Part 2: Metric thread M 68 to M 160 x 6 - Product grade B
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 06/01/2009
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 06/01/2009