Magnetic Base Test Indicator 0.0005" Fine Adjustment New Base has strong magnetic holding power, magnet on both side and bottom of the base 360 swivel, Dovetail and Shank Mount, Single action locking mechanism, One Knob control all arms Arm is 9-1/2" reach, it's blue color. fine adjustment is on both front and end of arm Test Indicator: Graduation: 0.0005", Reading: 0.030"