1.HIGH-QUALITY:Made of high quality manganese steel,strong compression resistance, not easy to deform, high plasticity, good resilience, uniform force, strong and durable. 2.STRONG ELASTICITY:The waist drum design brings greater jumping force to your trampoline (larger diameter, stronger jumping force), better elasticity than straight type, and better jumping experience. 3.SPRING HOOK:Made of high quality metal and PP plastic.Electroplating treatment of pole surface is not easy to rust.The handle is made of PP plastic material, one-piece molding,the hook handle is designed with finger grooves to increase comfort,Make installation easier and faster. PACKAGE:8pcs trampoline springs.Suitable for 15 inch and 16 inch trampolines.(Size:2.6x18cm)