Starrett 579F Self Centering Telescoping Gauge With 2 Telescoping Arm, 3-1/2" - 6" Range, 3-1/4" Handle Length

• It has a slightly greater range and two telescoping contacts in comparison with no. 229 series.
• Handle is rigidly attached to the contact plunger and is automatically self-centering.
• Constant spring tension gives uniform contact pressure.
• Both plungers are easily locked at any desired setting.

Telescoping gauge is used for determining the true size of holes, slots, and recesses up to 6". The ends of both contact is hardened and ground to a radius to allow proper clearance on the smallest hole the gauge will enter. This tool must be slightly "rocked" in the hole being measured to ensure that the tool is on the proper diameter before it is locked and withdrawn. The final hole size is obtained by measuring over the gauge contact with a micrometer.