Timestrips - Freshness Guaranteed

Sometimes terms such as ‘best before’, ‘use by’ or ‘eat within’ can be confusing when you forget when you opened a package. Timestrips are single-use, disposable labels that monitor lapsed time, ranging from under 1 day to 6 months. Basically Timestrips help people manage perishable goods in their home. All you do is peel off the backing paper and apply it to the package of food. The first window tells you that the strip has been activated and will start to let you know how many days the package has been opened.  (GUSH Magazine)

From the TimeStip Website:
Timestrips® are single-use, disposable, smart-labels, which automatically monitor lapsed time, ranging from under 1 day to 6 months.
The technology behind the revolutionary Timestrip® works by capillary action, allowing a tinted liquid to migrate through a micro-porous material at a consistent rate.
Inexpensive and easy to use Timestrips® are setting a new standard in product labelling on perishable goods.