Accurate humidity and temperature readings come from the Precision Thermohygrometer. It’s an ideal instrument for homes of asthma sufferers, museums, health clubs, storage facilities, etc. The upper scale shows humidity from 20% to 100%, as measured by the "Supratherm" element, which is accurate to + 3%. The lower scale is temperature, from –4° to 122°F (°C also). The polished brass case is 6” dia. x 1 5/8”D. The white dial is 4 3/4” dia. In the flange there are three holes for mounting (screws included) to a wall. (Matches both the BAM111 Marine Barometer and BAP111 Precision Barometer). BA930