The Wireless Temperature Sensors are used exclusively with the WSG30 system to measure the temperature of objects in a refrigerator or freezer. By placing the sensor in a bottle filled with glass beads or glycol users will receive a reading that represents the temperature of the contents of inside of the refrigerator rather than the ambient air temperature. When the temperature falls outside of the WSG30 system’s programmed high or low limit, the user will receive an alarm via text message or email. The external probe is wired to the sensor with the included 12’ of wire. The sensor includes two AA alkaline batteries which will power the sensor for up to two years. An optional plug-in power supply is also available, in which case the batteries then become a backup if the main AC power fails. The wireless sensor can be placed up to 300’ away from the WSG30 or further if multiple sensors are used to create a mesh network.