3657MTW Magnetic Base Flex O Post Indicator Holder.

Accommodates all Starrett test, back-plunger, AGD, dial and miniature-dial indicators as well as similar indicators of other manufacturers.
Fine adjustment.
Positive On/Off switch.

Assembled to the magnetic base, the post has a vertical reach of approximately 15 (380mm) and a horizontal reach of approximately 10 (250mm). The indicator snug on the end of the post can be rotated through 360 and locked in any position.