Harness the sun's natural energy with the SwimWays ThermaSpring Solar Mat. The ThermaSpring Solar Mat maintains and raises pool temperature by reducing evaporation, keeping heating costs down. The twist-and-fold spring technology of each solar cover ring is easy to use, and the decorative oval shape is perfect for all pool shapes and sizes. For maximum effectiveness use multiple solar rings. The recommended coverage is 70-80% of your pools surface.