Upper Bounce Trampoline Springs, heavy-duty galvanized, Set of 15 +Free Spring Tool! SAVE BIG when purchasing this Upper Bounce Trampoline Springs, Set of 15 + "Free Spring Tool" + "Free Shipping"! Spring is designed to give it that great bounce! Heavy Duty Galvanized Springs, Cold weather crack-resistant Use a T-Hook for best performance to install springs T-HOOK : This amazing tool helps you get the spring into the trampoline frame Easily and Quick when installing Your Jumping Mat