Glycol filled probes are designed to provide a buffered response to changes in the temperature.  This helps to simulate the thermal lag experienced by products stored in the monitored environment.  

For use with all products accepting a standard type k thermocouple input.

“The loss of only one dose of Pediacel vaccine a month in each general practice is worth more than £2 million a year.”

Protocol for ordering, storing and handling vaccines
Department of Health, England

This probe can also be used for other applications e.g. food and drink storage