BS EN 1661:1998 Hexagon Nuts With Flange (ISO/DIS 4161 : 1996, modified)
Current
his European Standard specifies the characteristics of hexagon nuts with flange, with threads from M5 to M20 inclusive, of product grade A for threads up to and including M16 and product grade B for threads above M16 and with property classes 8, 10, 12 and A2-70.