Certified Precision Barometer Precision Barometer No. 2039 is designed for accurate determination of the absolute air pressure. The metal diaphragms, which are manufactured in a special technical processes, react very sensitively to changes of the surrounding air pressure. This barometer determines the absolute air pressure, i.e. the air pressure which exists at the place of installation. An adjustment such as on normal barometers, which indicates the air pressure reduced to sea level, is therefore unnecessary. The 2039 Barometer is also suitable for exact determination of slight height differences within the height range of the dial. All models are jeweled movement.