Silica gels are a type of ‘humidity indicating desiccant' that you'll often see included in the bottom of shipping crates or storage boxes, parcels and packages. These sorts of desiccants, or drying agents, are usually included as a small porous packet containing a granular substance or paste, often stamped with ‘do not open' or ‘do not eat'.
The role of silica gels and other such desiccants is typically to absorb any residual moisture or humidity in the atmosphere, helping to protect packaged products or installed electrical systems by keeping the enclosed space as dry as possible during operation, storage or transport.
In more specialist cases, silica gels are also used to provide a clear visual indicator of specific saturation levels over time, and to show when reactivation or replacement of the gel is required.
Humidity indicating desiccants are widely used in a great many industries, applications and environments, including: