Colour-coded design, green, yellow and red show different ranges of tyre tread. Green for a healthy tyre 4.76-25.40mm, yellow for replace tyre 2.38-3.97mm and red for an illegal tyre 0-1.59mm. Chrome steel body with pocket-clip. Gives high accuracy readings in Metric and Imperial. Scale from 0-25mm in 1mm (0-1" in 1/32") graduations.