Time temperature indicator

A time temperature indicator is a type of sticker that is printed with a pattern of special ink that can tell you what temperature it is. The sticker changes color when the temperature inside a container changes. For example, if the container is too hot, the sticker turns red. If the container is too cold, the sticker turns blue. The time temperature indicator can tell you how long the container has been exposed to a certain temperature, so you'll know how long it's been too hot or too cold.