EZ-Drum Electronic Brake Drum Gauge Range: 4 to 20/100 to 500mm. Reads in Inch/Metric/Fraction. Resolution 0.0005/0.01mm (fractions in 1/64 increments). Dust water and oil to IP54 standards. Extra-long jaws which allow for increased measurement capability are etched with depth markings and have threaded holes for depth stop locations (1 and 1.5) to ensure proper measuring alignment. 4 preset without the need for a master for internal measurements.. Zero setting and reversible contact points for external measurements (can be used for some rotor and disc measurements). Hold function 74-150-020 Prop65 information pending -