It is a wireless digital thermometer with a freezer. It can be used in the freezer and act as an indoor and outdoor thermometer. Your own alarm sound can warn you in time when the temperature is exceeded. Characteristics: The minimum and maximum temperatures are displayed on the LCD screen and can be reset manually. With sound alarm inside and outside. When the temperature exceeds the pre-set minimum and maximum alarm setting, it will generate an alarm sound. A low battery level will be displayed on the LCD screen. It includes 24-hour minimum and maximum temperature records, so you can easily monitor temperature changes in your refrigerator and provide double protection for food safety. With an arrow indicating the trend temperature and daily information about the highest and lowest temperatures. Comes with an adjustable hook so the display can be mounted on the wall or positioned vertically for use on the table. Specification: Material: ABS Upgrade frequency: 10 seconds Transmission Range: 328 ft Indoor Temperature Range: 0 50 (32 122 ) External temperature range: -40 60 (-40 140 ) How to install the sensor: The sensors are equipped with spring-loaded clips along with a plastic handle for tight attachment to the edge of the shelf. The display can be mounted on a magnet on the refrigerator or use an integrated keyhole for wall mounting. The package includes: 1 x Host (Battery not included) 2 x sensor (battery not included) 1 x User Manual To notice: Do not install an inverted battery. Do not place the receiver near metal. Avoid transmitters directly in the rain.