Magnetic Base Indicator Holder 

This magnetic indicator holder locks all its joints when the knob is tightened.

The on/off switch makes it easy to position. The V-groove base allows you to mount it on cylindrical surfaces. The permanent magnet has an 80 kg (176 lb) holding force.

The lower arm is 110 mm long, the upper arm is 100 mm long. The threaded hole in the top of the magnetic base threaded for an 8 mm threaded post.