Screw Jack With Single Side Flange (with Ring Lock Nut) (S.G. Iron Housing Carbon Steel Spindle) Features : Centering hole dia, 12 mm. Bottom Flange can be bolted to the T-Slot for stability. Spindle: Carbon Steel Trapezoidal Thread Housing: High Tensile SG IRON. Pads Code P911-8/14 and 9/26 can be used for safe locating of U-Clamps.