Accusize - Self-Reversing Tapping Head, 4-1/2"(M5-M12), 1/8"NPTXJ6, 2600-4012 Depth Control: Top will advance 0 .140''  0.004'' after machine spindle travel stops. Example: to achieve a top depth of 1.000 '', set spindle stop at 0.860'' will advance an additional 0.140'' to 1.000'' depth NC Machine. Set torque as high as possible within safe limits of the top.NC machine cutting feed equals (top pitch x spindle RPM). Reverse feed equals 2 X (top pitch X spindle RPM). 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. Head comes complete with 2 collets. Tapping Capacity in steel: #4-1/2'' (M5-M12), 1/8'' NPT, Jacobs Taper#J-6, REC. Max. Speed: 1000RPM.