Wall Bag is another great way to help your winter cover stay securely mounted to your above ground pool, making pool re-opening in the Spring much easier. Simply fill it with water and place it on top of your winter cover (along its perimeter) to protect it from high winds that can loosen even the most tightly sealed cover. Made from thick vinyl sheeting, it is designed to handle years of freezing temperatures without splitting or leaking and can be easily filled with a garden hose. Best of all, Water Bag have built-in grommets to let you connect it to your winter cover cabling, keeping it in place.