Check the listing for details. starrett 657 magnetic base. Condition: New – Open box. Listed at 194.99 USD. Suitable for either of the Starrett dial indicators, this magnetic base has a push-button switch for easy one-handed operation. In addition to its bottom surface, both sides of the base can be used for mounting. A V-groove in the top face is used for attachment to machine arbors or shafts. The articulating arm lets you position the indicator at any angle or orientation. Made in USA.