Humidity Indicator are designed for mounting in moisture sensitive electronic or electro-optic equipment or any other humidity controlled enclosure. They readily detect changes in the humidity of the space being monitored by using a colour change indicator paper, which turns from blue to pink as the humidity increases and turns back to blue when the humidity decreases.
Most of these indicators can be fitted with a desiccant cartridge, which will adsorb any moisture entering the equipment during its use. These are known as static desiccators.