The Ruffwear Swamp Cooler provides protection from the sun and cooling through evaporation. In warm climates, dogs typically stay cool by seeking shade during the heat of the day and moving around in cooler temperatures. The Swamp Cooler allows dogs to perform in hot climates. To activate the Swamp Cooler, soak in water, wring out and place on your dog. The light-colored fabric reflects solar radiation, while evaporative cooling pulls heat from the dog.