Bestyet Flexible Magnetic Indicator Stand Features include... 9-3/8" Arm Reach Instant fixation in any position Single knob controls all three joints Heavy-duty mechanical lock Sturdy aluminum arms for maximum rigidity Fine adjustment Fits dovetail and 3/8" stem indicators Mounting thread M8 x 1.25 mm Magnetic base has 175 lbs. of pull, vacuum base has 3-1/2" dia