Humidity Indicator Card (HIC) is a kind of visible card with several dots that can change the color from "Dry" to "Wet", 

 

The dot color will change along with the RH degree from brown to green (cobalt-free cards). It is provides the users a low cost and easy way to indicate the effectiveness of the packaging.

Cobalt-free HIC cards do not contain heavy metals. These cards help monitor desiccant activity and are ideal for use with desiccants in any application where moisture control is critical.

Humidity Indicator Cards are widely used in high-end moisture sensitive electronic components, optical components, instrumentation packaging etc.

 

It can help the users to know the inside humidity condition and decide whether the desiccant should be replaced or not.