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 feet), 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 limits. Upon initial activation of the temperature alarm, no alarm will occur regardless of current temperature; 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 set of outdoor temperature readings. Even when the sensor is placed outdoors or in a separate location such as a warehouse, you can monitor temperature conditions without leaving your home. Maximum and minimum temperature data are updated every 24 hours. The device does not store historical temperature data, and extreme values are not permanently retained. Equipped with hanging holes and brackets on the back, the unit can be mounted on magnetic surfaces such as refrigerator doors or microwaves, or it can be wall hung or placed on a flat surface. Easy to install and use. Power supply: 2 x AAA batteries and 4 x AA batteries (not included) Color: White + Black Material: Plastic Type: 1 to 2 Package Contents: 1 x Thermometer 2 x Transmitter 1 x English Manual Only the above package content is included; other products are not included. Note: Lighting effects and display settings may cause slight variations in the color shown in images compared to the actual product. Measurement error allowance is +/- 1-3 cm.