ISO 3442-3:2007 specifies 90 and 60 serrations and jaw nuts applicable to 90 and 60 serrations for mounting the top jaws on the base jaws of power chucks, in order to ensure interchangeability. It also describes, with reference to ISO 230-1, the geometric tests for self-centring, power-operated chucks with two or more two-piece jaws (serrated type), and the corresponding tolerances which apply.