Indoor temperature detection range -10°C-60°C (32°F-122°F); Outdoor temperature detection range -40°-60° (-40°F-140°F); Transmission range: 100 meters/328 ft., no obstructions. This wireless refrigerator thermometer has an audible alarm and can manually set the maximum/minimum alarm value. It will ring when the temperature value reaches your preset maximum/minimum alarm value. But when the temperature alarm is just turned on, no matter whether the temperature reaches the alarm's temperature range, it will not alarm and will ring after 10 minutes. This digital refrigerator and freezer thermometer comes with remote sensors, which can display indoor temperature and 1 sets of outdoor temperatures at the same time. Even if the sensor is placed outside or in a warehouse, you can record the temperature without leaving your home. The maximum/minimum temperature data is updated every 24 hours, but there is no function to record the maximum/minimum temperature data, and the maximum/minimum temperature cannot always be maintained. With hanging holes and brackets on the back, you can attach the main body to the surface of magnetic objects such as refrigerator doors and microwave ovens, or you can hang it on the wall or stand on a table. Easy to install and use. Power supply: 2 X AAA batteries and 2 X AA batteries (not included) Power supply: 2 X AAA batteries and 4 X AA batteries (not included) Colour:white+black Material:plastic type:1 to 1/1 to 2 Package Contents: 1 x thermometer 1 x transmitter 1 x English manual / 1 x thermometer 2 x transmitter 1 x English manual 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.