Well, they didn't last long, replaced all three roof vent covers, UV damage was incredible, the rig is only three years old and the vent covers were so degraded that one broke, (they were very brittle) when a heavy wet snow accumulated on the roof. On a side note, the windows still look new. Any body else replace them yet? My previous TT was seven years old, the vent covers were faded and cloudy, but they were still in one piece when I sold it.