1.Wireless signal transmission distance without interference 100 metres, can display two different maximum and minimum temperature records at the same time. 2./F unit conversion: Celsius and Fahrenheit display can be switched to meet daily needs and has strong signal penetration. 3.Alarm settings: When the indoor or outdoor temperature exceeds the preset minimum and maximum alarm values, the thermometer will emit an audible alarm and a visual alarm to alert you and allow you to see if adjustments are needed. 4.EASY TO INSTALL AND OPERATE: Use the magnet on the back to magnetically attach the thermometer directly to your refrigerator or freezer, or place it on a table. 5.APPLICATION: Can be used in the refrigerator, freezer or indoor and outdoor, easily monitor temperature changes and provide double protection for your food. Measuring Range (Transmitter): -40-60 ( -40- 140) Tolerance: 1 ( 2 ) Temperature Resolution: 0.1 Wireless frequency: 447.6MHZ Wireless range: 100 metres without obstacles Main unit size: 95x62x20mm Transmitter size: 95x36x20mm Use of power: (default without battery delivery) Host: 2x AAA batteries Transmitter: 2x AA good batteries Colour:White Material:ABS Package Contents: 2 x Thermometer 4 x Transmitter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.