Lufft certified thermohygrometer Model #176 has a 6" dia. overall case of solid brass drilled for wall mounting. The 5" dial has a glass cover. The dial face is white with black figures, blue highlighted humidity graduations and red highlighted temperature graduations. The hygrometer of this instrument has a Durotherm element and is certified to be accurate within ±3% RH. The dial indicates the complete range of 0 to 100% relative humidity. Humidity graduations are in 1% RH. The bi-metallic thermometer is accurate to 1% of scale with a range of –20 to 100°C and 0 to 210°F. The dual temperature scale is in graduations of 1°C and 2°F. Each instrument has been tested at three different positions of the dial under ISO 9001 control.