Testo plastic wireless humidity/temperature probe with internal probe connection. Probe type: NTC/humidity sensor. Measuring range: -4 to +122/0 to 100 percent RH. Accuracy: +/-0.9 degree F/+/-3 percent RH. Resolution: 0.1 degree F/ degree C / 0.1 degree F/ degree C/0.1 degree F/ degree C td. Battery life (Type: 4 AA batteries): Battery life at 77 degree F, 3 years; for freezer applications, 3 years with L91 Photo lithium Energizer batteries). Protection class: IP54. Measuring rate: Standard 15 min, 1 min to 24 h can be set. Operating temperature: -4 to 122 degree F. Storage temperature: -40 to 131 degree F. Display: LCD, 2 lines; 7-segment with symbols. Transmission distance: approx. 328' free field at a frequency of 2.4 GHz. Included wall bracket. Measures 3-3/32" length by 1-1/2" width by 3-19/64" height.