These springs are designed to fit all trampolines that use 5.5" or 7" springs. If you are unsure of what size spring you need, simply remove one of the old springs from your trampoline, make sure it isn't stretched in any way, and measure it from end of hook to end of hook; you may want to do this with 2 or 3 springs to make sure you get an accurate measurement. All of our springs are made from galvanized steel to protect against rust and corrosion, and unlike inferior springs, our springs have the most coils per inch available, ensuring you will get the best bounce possible.