The Starrett 657A Magnetic Base Indicator Holder with Swivel Post Assembly provides universal adjustment in both horizontal and vertical planes. The Starrett 657A is for use with all Starrett Test, Back-Plunger, AGD, Dial and Miniature-Dial Indicators. The Starrett Starrett 657A also accommodates similar indicators of other manufacturers. Powerful, permanent magnetic base holds firmly to steel or iron surfaces – horizontally, vertically, upside-down and has a push-button that turns magnetic force on or off for quick, one-hand set-up and take-down. Features: * Upper arm is 2-inch (50mm) long with a 5/16-inch (8 mm) dia. and swings more than 180 degrees held in place with a friction joint * No. 657F Indicator Swivel Post Assembly is 6-1/2-inch (165mm) high (less threaded end) * Extra 1/4-20 NC tapped hole in side of base for indicator mounting post * Swivel Cap Slot permits 90 degrees post travel to horizontal position * Three precision ground magnetic contact surfaces (plus V-step) * V-step adapts base to horizontal or vertical arbors and chucks * 7/32-inch (5.5mm) dia. step, 1/2-inch (13 mm) long * Fine-Adjusting Screw. Turn to zero set indicator * Black wrinkle finish on non-working surfaces * Post rotates 360 degrees What"s In The Box: * Starrett 657A Magnetic Base Indicator Holder with Swivel Post Assembly