AcuRite 00986M Refrigerator/Freezer Wireless Digital Thermometer Monitor refrigerator temperature and freezer temperature. Lithium batteries recommended for temperatures below -4F/-20C Audible and visual alarm when temperatures exceed your preset minimum or maximum temperature range Wireless thermometers clip to shelf or suction to wall inside refrigerator or freezer. Data Reporting: 90 second updates Mount display unit directly to your refrigerator or freezer using integrated magnets or hang on wall using keyhole Measures temperatures from -40 to 100 degrees Fahrenheit; -40 to 37 degrees Celsius