Heavy Duty Blue Solar Cover for 12 x 24-ft. Pool Heavy Duty construction designed to increase temperature by up to 10 degrees Since 1973 Robelle has been selling the best Solar Covers available for pool owners. This solar cover includes a 3 year warranty. Buy from the brand with over 50 years of experience. Cuts evaporation by up to 95% Extends swimming season Helps retain solar energy and keep heat in your pool Decreases chemical consumption Exceeds expectations set by regional and local water departments when advised to use a cover to conserve water