Evolution Industries Patented design Slide ‘n Dial Indicator Holders are proudly manufactured in the U.S.A. CNC machined from billet aluminum for use in all milling applications, CNC or Knee style mills. Available in 1″ or 2″ sizes. Quick, easy and accurate adjustment from 0” to 24” with optional extensions. The Indicator holder slides the full length of the extension arm and allows fine adjustments to keep the indicator on center line. Indicator holder bodies are red-anodized for easy identification in the tool box.