Articulated arm style alnico magnetic base, positions and locks easily. Includes ON/OFF switch and central locking knob to tighten both arms. Includes two balls joints and one central cylindrical joint. Dial gage holder includes fine adjustment and full 360° swivel. Hydraulic clamping system suitable for dial gauges with stem of 1/4" (6.35 mm), 5/16 (8mm) and 3/8" (9.5mm) and dovetail indicators. Magnetic pull approx. 130 lbs. (60 Kgs.)