Fowler 74-004-500 X-Tread and Poly-Cal Kit Electronic Caliper range: 6"/150mm, Tire Tread Gage range: 1"/25mm Resolution: .0005"/.01mm (Fractions by 1/64th increments) Polycarbonate frame Absolute/Incremental Measurement Tire Tread Gage: spring-loaded and hold measurement button for ease-of-use