ISO 10664:2014 specifies the shape and basic dimensions of the hexalobular internal driving feature for bolts and screws, including the gauging method. The curvature of the contour of the hexalobular internal driving feature is defined and additional information which can be used when drawing the contour given.
The intent is to provide the details necessary for inspection of the hexalobular driving feature. ISO 10664:2014 is not suitable for, nor intended to be used as, a manufacturing standard.