Can be programmed to record in either metric ( mm ) or U.S. ( inches ) of Hg.

Standard Sensor: Range: 26" to 32"(660 to 810mm), Accuracy: ±0.05"(±1.3mm).
Extended Range Sensor: Range: 18.75 to 33.1 in.-Hg(476 to 841mm-Hg), Accuracy: ±0.057"(±1.4mm).