As one of the safest and bounciest trampolines on the market, The Propel Trampolines 15' Trampoline with Enclosure will be a purchase you never regret. To give it this high rating, it has 108 galvanized steel springs and a thick Sure-Lock frame pad to ensure that safety and fun are tied for first place. The included Impact-Absorbent Enclosure System also aids in keeping that safety level high.