iGaging 0-4" Electronic Digital Depth Gauge SnapDepth 0.0005" Inch/Metric/Fractions Tire Tread Gage Includes 1" and 2" interchangeable depth bars to extend the rod to 2", 3" or 4". 3-Reading functions: inch, metric, & fractional Spring loaded movement for easy use Reading: 0.0005" / .01mm / 1/64 Use as an indicator or depth gage