RIDGID 67915 Rod Size of three quarter inch BSW (British Standard Whitworth and Imperial based screw thread standard) - 10 TPI (Threads Per Inch) Right Hand Cut, High Speed dies are designed as Bolt dies and are compatible with RIDGID Universal Die Heads (Nos. 504A, 711, 811A, 816, 817 and 911 Die Heads). The Die Heads can be mounted onto several different threading machines also from RIDGID The Dies in the head can be easily changed and if the Die Head is mounted to a machine the Die Head does not need to be removed from the machine for die changes.