Bestway Fast Set Solar Pool Covers utilize the sun's energy to maintain and increase the water temperature of your pool. By absorbing sunlight, these covers transfer the generated heat to the water. The cover is made from a durable material similar to bubble wrap, with tiny air bubbles that help insulate the pool by trapping heat and warming the water. These bubbles also transfer heat by absorbing sunlight. Additionally, the air bubbles insulate the pool, reducing water temperature loss and preventing dirt and debris accumulation. The cover also helps reduce evaporation and, by shielding from dirt and grime, can decrease the need for water cleansing chemicals. The solar cover's bubble design can keep a pool insulated even after the sunny season, prolonging the use of an above-ground pool. Setting up the cover is simple; just spread it on the water when the 8ft Fast Set pool isn't in use. It floats on the water, eliminating the need for tie ropes. This item measures 82 inches when placed inside the top rim of the fast set pool.