The heavy gauged and galvanized 7-inch springs of Zupapa safety trampoline provide superior bounce and are rust-resistant, having one year warranty. The 10FT has 60 pieces of 5.5 inch, the 12FT has 72 pieces of 7 inches, the 14FT has 96 pieces of 7 inches, the 15FT has 108 pieces of 7 inches. More Zupapa springs enable your trampoline super stretch, much more comfortable and safer.