ISO 2492:1974

Thin taper keys with or without gib head and their corresponding keyways (Dimensions in millimetres)

Also specifies the material of the keys, gives the relation which should be observed between the diameter of shaft and the section of key, and is of general application for cylindrical shaft ends. It is recommended that the values given be adhered to even for special applications. For normal taper keys and corresponding keyways refer to ISO/R 774.