SPI Deluxe Dial Indicator AGD 2: Dial Diameter 2.20" Features Include... Measuring Range: 0.500" Reading: 0-50-0 Revolution Graduation: 0.001" Face Counter: Yes Color: White. Accuracy Meets or exceeds Federal Specifications. Easy reading graduations Thread Size: 4-48 Stem Diameter: 3/8" Dial Diameter: 2.20" Adjustable bezel for convenient zero setting with clamp screw. Lug back supplied except where noted. Certificate of Calibration