Mitutoyo Internal Dial Caliper-Type Gage For checking internal bores, recess diameters and grooves. Features include... 0.20" - 0.60" Measuring Range 0.0002" Graduations +0.0008" Accuracy Max Measuring Depth: 1.37" Max Groove Depth: 0.09" Minimum Groove Width: 0.032" Ball Contact Points Spring loaded opening Press Button for closing arms. Arms automatically open when button is released Unit is spring-loaded and makes point contact at constant measuring pressure