You could never tells Tonic+ is a lesser quality natural gut from Babolat. The 15L gauge held tension after prestretching better than the highest quality multifilaments like X-One Biphase and Gamma professional. The obvious benefits from this quality gut is feel and power. I had confidence and comfort on every stroke and serve I used. Nice to have soft, anchored strings that made playing tennis a real joy. Don't be concerned about the thicker gauge unless you string a 18x20 smaller string bed. I had great spin production and no bad signs of fraying after two hours of play. You have to try this stuff at least once. I'm hooked even though they won't last as long as polys or slightly cheaper multi(s).