REED Instruments 8706 Digital Psychrometer/Thermo-Hygrometer, (Wet Bulb, Dew Point, Temperature, Humidity) Temperature Measuring Range: -4 to 158F (-20 to 70C) Dew Point Measuring Range: -109 to 122F (-78 to 50C) Wet Bulb Measuring Range: -69 to 122F (-21 to 50C) Dimensions: 7 x 1.9 x 1" (179 x 48 x 25mm) Operating Humidity Range: 10-80%