This is a 20 pack of Humidity Indicator Cards
These Humidity Indicator Cards measure 50 x 78 mm and have 3 indicating spots which change from Blue (dry) to Pink (humid)
They are a great tool to use with a Desiccant Packet to help control moisture
They are used in close contact with a Non-Indicating (White) Silica Gel product to highlight moisture levels within a closed environment
When the product is dried and placed back in contact with the card, the indicator buttons revert to their original colours
Please note: Indicator cards should not be placed on metal