This International Standard is a supplement to ISO 2568 and ISO 4231 and lays down the dimensions of hand- and machine-operated circular screwing dies intended for production of taper pipe threads, R series, in accordance with ISO 7-1. With the exception of the die 1/16, the general dimensions of these dies (diameter, thickness and fixing dimensions) are in accordance with ISO 2568 so as to permit the driving of hand-operated dies with the aid of the die stocks defined in that document.