The Tracker Safe 18" Dehumidifier Rod works by slightly increasing and maintaining the air temperature inside the gun safe or other enclosure. This allows the warm air to circulate throughout the safe on a continual basis to eliminate humidity, mildew, and condensation which are dangerous to your expensive firearms or precious metals collection. The 18" Dehumidifier Rod has a detachable plug so that the cord can run through the back of a safe through a small hole. Dries approximately 200 cubic feet.