SPI Test Indicator & Quill Clamp Holder Set Dial Test Indicator Features include... 1" Dial Diameter Range: 0 - 0.030" Reading: 0-15-0 Contact Point: 0.080" dia. X 1/2" long Graduation: 0.0005" 2 dovetail stems: 3/8" and 1/4" dia. Includes Certificate of Calibration Quill Clamp Holder Features include... Fits milling machines with 1-7/8" dia. spindle. Clamps directly onto machine quill. Has clearance to avoid a tool in collet or chuck. Will not disturb working tool in the machine.