The present invention relates to a device specially designed for use in cold chains to indicate any break in said chain, i.e., any thawing and refreezing of the product under control. The invention comprises a small, closed, transparent container, having therein a weak dividing partition determining two independent compartments, one of which is filled with water while the other is filled with a colored liquid with a freezing point considerably lower than that of water, such as a dyed alcohol, for example, such that when the device freezes the expansion causes the partition to break such that thawing occurs, and the liquids will mix together, indicating said thawing.
