Temperature range -50 to +150 degrees Celsius with the external sensor 3½mm connector integrated Air temperature range through internal sensor -10 bis +50 degrees Celsius Humidity range 5% to 99% RH Tolerance +/- 2% Temp Tolerance +/- 0.3 degrees Celsius Automatic Dewpoint calculation Multilingual display Auto Power Off The CMEX II detects and evaluates the moisture conditions within the slab or screed by non-destructively measuring the electrical impedance. A low frequency electronic signal is transmitted into the material under test via the electrodes in the base of the instrument. The strength of this signal varies in proportion to the amount of moisture present in the material. The CMEX II determines the strength of the current and converts this to a moisture content value for concrete slabs and a comparative value for other cementitious floor screeds, displayed on a large clear digital dial.