FREE SHIPPING on all Systems & Sets!! Tired of popped pillows or sunken winter covers? Or scooping leaves from your swampy above ground pool? The PoolTree System helps your cover clean itself by holding the cover off the surface of the water so it can drain and dry (when using a mesh cover). The durable ball & bungee system was invented in Connecticut and tested to withstand the harshest winters without losing its effectiveness. Select the size of your pool to learn more.