The Robelle 8 Mil Deluxe Space Age Round Bubble Solar Blanket warms up your pool water by up to 12 degrees. Made of polyethylene material, this solar cover floats bubble side down on the surface of your pool water when the pool is not in use, allowing solar energy to pass through and trap it as retained heat in the pool. This cover is Deluxe and made of Heavy Duty 8 mil material that helps raise the water temperature by absorbing sunlight during the day and retaining the heat at night, thereby extending the pool season. Savings come from a reduction in water evaporation decreasing chemical consumption. Material is highly resistant to ultraviolet rays which inhibits deterioration. 5-year warranty.