Gives the overall dimensions for circular screwing dies for all sizes of thread up to 2 in. B.S. Parallel pipe thread, and the dimensions for hexagon dienuts. Provision is made in Table 1 for nine outside diameters of circular dies, applicable to all sizes of thread up to 2 in. B.S. Parallel pipe thread, any particular thread being associated with not more than three diameters of die. Table 2 provides for a comprehensive range of hexagon dienuts for all sizes of thread up to 4 in. B.S. Parallel pipe thread.