Traceable® Precision Barometer's triple scales provide a sensitive measure of atmospheric pressure from 954 to 1073 millibars, 28.1 to 31.7 inches of mercury, and 715 to 805 millimeters of mercury with a resolution of 0.5 mbar, 0.05 InHg, and 0.5 mmHg. Accuracy is ¬±0.5% of reading. To assure accuracy an individually serial-numbered Traceable® Certificate is provided from the manufacturer's ISO 17025 calibration laboratory accredited by A2LA. It indicates traceability to standards provided by NIST (National Institute of Standards and Technology). Housing is rugged corrosion-proof, nickel-chrome. Adjustable pointer may be set to indicate changes. Complete with altitude adjustment screw (use at locations as high as 1000 meters), notched desk stand, and wall mount. Size is 4‚Öõ inches diameter by 1-1/2 inches. Weight is 1 pound.