Debris Protection Shield: Above-ground swimming pool cover will prevent debris, leaves, and trash from getting into and contaminating the pool water Thermal Insulation Barrier: Round pool cover is made of durable, reliable materials that prevent heat from escaping while keeping the water comfortably warm Evaporation Control System: Above-ground pool solar cover prevents water evaporation due to dry winds and guards against free-chlorine loss caused by UV rays Compatible Pool Size: Dimensions (L x W): 18 x 18 feet; Recommended for use with above-ground pools that measure 18 feet in diameter; Pool is not included Season Extension Cover: Secure the round cover over the top of the pool to extend your swimming season by keeping the water and heat in and debris out