Accusize - Self-Reversing Tapping Head, 5/16"-3/4"(M8-M20),1/4'', 2600-4022 Guaranteed depth control; within 0.004'' Chatter-free clutch has positive engagement which allows for a smoother, more accurate operation and more rapid reversal Radial Float is self-centering to compensate for hole center misalignment Unique Double Spring mechanism produces automatic feed and cushion drive. There are 2 springs for the feed and 2 springs for the reversal Pre-set torque control permits easy operation of tap brake torque control