ISO 12126:2012 specifies the characteristics of prevailing torque type all metal hexagon nuts with flange (style 2), and metric fine pitch thread with nominal thread diameters from 8 mm up to and including 20 mm, in product grade A for diameter sizes less than or equal to 16 mm and product grade B for diameter sizes greater than 16 mm, and with property classes 6, 8 and 10.