SkyBound Premium 7.5 Inch Trampoline Springs for 13 x 13 Ft. Skywalker Trampolines Set of 6 Specifically Designed for Square Trampolines | Don't Use More than 3 of These on Each Side! 7.5" Length Springs | Measured End to End Including Hooks | Qty of 20 40 Coil Count | More Coils than Competitor Springs 29.7mm Diameter | Wider Than Competitor Springs A Full 1 Year Warranty + Free Spring Tool with All Premium Spring Orders!