Its' the sun, they just turn to dust. Here in So Cal I even got the upper one with the white tyvec top. The side that gets the sun is done in just about 2-3 years depending how much it's on the TT. I think the cover would last longer inside a covered storage with no windows. There is a big tag on my cover that says "Made In China". At least the cover doesn't kill the TT. The cover for my TT costs about $350. If it lasts 24 months that's about $15 a month.I don't care what they say, putting that thing on and off is a real pain and that's when they fall apart.