Wifi Freezer Alarm and Refrigerator Temperature Monitor, Freezer Sentry Wireless Temperature Monitor installs in under 5 minutes without tools or special expertise. Any homeowner or small business owner can hook the 10-foot sensor to a wire shelf inside the refrigeration unit and mount the exterior control box to the outside of the unit or on a wall with included hardware. Then download our iOS and Android compatible app and complete the notifications set-up. Breathe easy knowing that a freezer alarm alert when temperatures drop will help protect you from expensive inventory loss.