This glass bead filled plastic vial will buffer any momentary fluctuations in temperatures that may caused by standard refrigeration operations such as defrost cycles, opening of doors, and fans circulating air. The 3mm glass beads will slow the response time of the temperature sensor allowing more accurate temperature data to be captured and prevent false alerts from being sent. This is a highly recommended accessory for every cold storage application. For use with any Monnit wireless temperature sensor with probe.