Indoor temperature detection range -10C to 60C (32F to 122F); Outdoor temperature detection range -40C to 60C (-40F to 140F); Transmission range: 100 meters/328 ft., no obstructions. This wireless refrigerator thermometer features an audible alarm with manual setting for maximum and minimum alarm values. The alarm will sound when the temperature reaches the preset threshold. Upon initial activation of the alarm function, no alert will occur immediately; the system will begin monitoring after a 10-minute delay. This digital refrigerator and freezer thermometer includes remote sensors that simultaneously display indoor temperature and one outdoor temperature reading. Even when the sensor is placed outdoors or in a separate location such as a warehouse, you can monitor temperature readings from inside your home. Maximum and minimum temperature data are updated every 24 hours. However, this device does not continuously store historical maximum and minimum temperature records, and these values may reset under certain conditions. Equipped with hanging holes and a built-in stand, the main unit can be mounted on magnetic surfaces such as refrigerator doors or microwave ovens, or placed upright on a flat surface. It can also be hung on a wall for convenient viewing. Easy to install and operate. Power supply: 2 x AAA batteries and 4 x AA batteries (not included) Color: White + Black Material: Plastic Model: 1 to 2 Package Contents: 1 x Thermometer 2 x Transmitter 1 x English Manual Only the items listed above are included; other accessories are not included. Note: Due to lighting effects and monitor settings, the color of the item in the photo may slightly differ from the actual product. Measurement errors within 1-3 cm are acceptable.