Wireless Refrigerator/Freezer sensor/alarm

Monitors the internal temperature of your refrigerator/freezer/wine cellar and lets you know if there's a problem.

A wireless remote thermometer for gas refrigerators freezers

Wireless Refrigerator/Freezer sensor/alarm from Sensible Living

Mini-wireless sensor development board

Mini-General Purpose Wireless Sensor board

Sump Alarm Temperature and Humidity Sensor: Wireless Temp Monitor, Freezers/Refrigerators Model: LS-SENTRY-120V-FREEZER-10FT-RAW

The best wireless temperature alarm monitors for freezers

Mini-wireless sensor development board

Mini-General Purpose Wireless Sensor board

SCD41 CO2 Sensor Breakout from ModuleFun on Tindie

Cheap 433Mhz sensor kit from Nico on Tindie

Refrigeration - Refrigerator / Freezer Walk-In WiFi Monitoring

Wifi Freezer Alarm and Refrigerator Temperature Monitor – Wireless Hyg

The 7 Best Fridge Thermometers