20CM Indoor Outdoor Thermometer Antique Hygrometer Painted Iron Case Temperature And Humidity Measuring Instrument US/EU DialFeatures: New Quality. No battery, energy saving and environmental protection. A simulated hygrometer can help provide a healthy environment for temperature and humidity. Temperature and humidity sensors made of high-precision materials. Description (Approx.):Material: Iron Case, Plastic Shell Bottom, Glass Mirror, PVC Watch Style: American dial European dialMeasuring Range: Temperature-40 - 120F (-40 - 50C), Humidity 0 - RelAccuracy: Temperature +/- 5F (+/- 2C), Humidity +/- 7% (40% to 70% Rel)Size: Diameter is 203mm / 7.99inch, Thickness is 43mm / 1.69inch Weight: About 0.38kg Working Principle: Coil spring made of special material uses the physical properties of "thermal expansion and contraction" and "swelling and contraction" to make the coil contract or expand to push the pointer to rotate. Product Feature: The product is used to measure the changes of temperature and relative humidity in the environment, so that you can live more scientifically. Clearly understand the heat and cold and feel wet or dry. List:1 pc. Thermometer and hygrometer