Trampoline owners, these replacement springs are absolute lifesavers when your old ones start losing their bounce! The 13.5cm size is common for many backyard trampolines, but definitely measure your existing springs before ordering. Made from durable alloy that provides great rust resistance and maintains springiness season after season. The included hook is genius - makes installation so much easier than struggling with pliers or sore fingers. The package includes 5 springs plus a triangle buckle, webbing, and hook - everything you need for common trampoline repairs. The tension is perfect - provides that satisfying bounce without being too stiff or too loose. I replaced the worn springs on our 5-year-old trampoline, and it's like having a new trampoline again! The kids noticed the difference immediately. The alloy construction feels substantial - not that cheap feeling some replacement parts have. The springs fit securely in the trampoline frame holes and mat eyes without slipping. Installation took about 20 minutes for all five springs with the handy hook tool. Much cheaper than replacing the entire trampoline, and honestly better quality than the original springs that came with our trampoline. If your trampoline isn't bouncing like it used to or you have broken springs, this kit will extend your trampoline's life for years. Essential maintenance for any trampoline family!