Historical
BS EN ISO 4034:2001
Hexagon nuts. Product grade C (British Standard)
This International Standard specifies the characteristics of hexagon nuts with threads from M5 up to and including M64 and product grade C.
If, in special cases, specifications other than those listed in this International Standard are required, they should be selected from existing International Standards, for example ISO 724, ISO 898-2, ISO 965-1 and ISO 4759-1.
British Standards Institution [bsi]