Wet air passes directly through the desiccant medium which adsorbs the moisture. The desiccant medium has a finite capacity for adsorbing moisture before it must be dried out, or regenerated. Heat of compression dryers use the heat of the compression. Desiccant air dryers BD+ and CD+ are designed to work with oil-lubricated and oil-free air compressors. Desiccant air dryer XD+ is designed to specifically work with oil-free air compressors. Many tools and equipment, driven by compressed air, cannot withstand water or moisture. Many processes, using compressed air, are processing products that cannot withstand water or moisture. Inherent to the compression cycle, free water is often formed in the compressed air circuit.