Keep an eye on the outdoor and indoor temperature with ease. This thermometer is comprised of two parts. An LCD display/receiver to keep inside and a wireless outdoor temperature sensor which transmits the outdoor temperature back to the display. No need to expose the LCD to the elements. Great for monitoring computer server rooms, wine cellars, effectiveness of housing insulation, or for simply wanting to know the differentiation in temperature. Transmission frequency: 433.92MHz Receiver dimensions: 86(H) x 57(W) x 18(D)mm Sensor dimensions: 68(H) x 50(W) x 21(D)mm Outdoor / Exterior Scale : -40.000000 degrees Celsius, 60.0 degrees Celsius Indoor / Interior Scale : 0.0 degrees Celsius, 60.0 degrees Celsius Display Type : LCD Width : 57.0mm Height : 86.0mm Depth : 18.0mm Disposable battery required to power : Main Product Battery type : AAA Battery Quantity : 2.0pc Are batteries included : false Batteries can be replaced : true Battery compartment location : Back Battery type : AAA Battery Quantity : 2.0pc Battery used for : Transmitter Batteries can be replaced : true