Use these reusable desiccant packs in your air tight equipment cases, such as Pelican and Tundra Brand. The desiccant pack will adsorb any residual dew from your last observing session, protecting your equipment from water damage. When the pack has reached its limit the crystals turn pink, indicating that it is time to regenerate the pack for another use. Regeneration is accomplished by placing these special packs in the microwave for 30 seconds several times. The pack will turn blue again and it is ready for another use.