Koval Inc. 7" Trampoline Spring Replacement Heavy-Duty Galvanized Trampoline Spring Replacement: Replace your trampoline's old, weary, unsafe springs and bring your trampoline back for bouncing days. High Quality: We care about our customers safety and provide them with strong springs with the best quality steel, thickest steel guage, and the most coils. 7" Measurement: Before purchasing, please measure your hooks end to end to get the correct size. 20 Quantity: Our trampoline set comes with 20 springs.