ISO 4033:2012 Preview
Hexagon high nuts (style 2) -- Product grades A and B
This standard was last reviewed and confirmed in 2017. Therefore this version remains current.
ISO 4033:2012 specifies the characteristics of hexagon high nuts (style 2), with threads from M5 up to and including M36, with product grade A for threads of diameter less than or equal to M16 and product grade B for threads of diameter greater than M16.