FREE SHIPPING on all Systems & Sets!! If you want to ensure the best performance out of your PoolTree System, or if your existing cover needs to be replaced, purchase the cover and System together in a package. PoolTree Packages include both a PoolTree Winter Cover Support System for round pools AND a high-quality mesh (porous) winter pool cover. When purchased as a package, the cover and System are less expensive than if purchased individually. Select the size of your pool to learn more.