Switch on/off to move the base without reaction force, avoiding damaging the gauge and working desk. Total Height: Approx. 360mm / 14.1 inch; Clamping Hole Diameter: Approx. 8mm The magnet base has very easy switching operation, and the alloy magnet is magnetic and stable. Rod inside the arm has tapered ends. As the knob is tightened wedges against the taper forcing the rods out to clamp on the ball Precise structure of this Magnet Measuring Stand Test Gauge Holder makes it pretty easy to use and maintain, high sensitivity, stable and reliable. It is your ideal tool for measuring precision workpiece fields, dial rod can be adjusted to multiple directions and angles to meet your different needs The smooth, universally lacquered chrome arm can be attached at any angle, is easy and quick to use and is often used for mechanical corrections, technical measurements, mechanical processing, work piece measurement, device correction and other fields