Dri-Z-Air removes moisture from the interiors of trailers and campers during periods of storage or lay-up. Keeps moisture from clothes, sheets, shoes, etc. Also prevents condensation on windows, walls and ceilings. The Dri-Z-Air tray fits under the unit to avoid spills. Made in the USA from recycled plastic. Full 360 degree venting for optimum air-flow. Sturdy containers can be refilled with DRI-Z-Air brand premium grade refill crystals.