Not sure if your are talking about lids or covers, vent lids don't last very long for the most part, particularly if there are no vent covers to protect them. Whether we purchased new or used, I have always added or replaced original vent covers with vent covers where vent lid can be fully raised allowing our bi-directional fans to operate unrestricted. Pretty simple DIY and not too expensive for RV shops to perform either, additionally I can spend time inspecting my roof and seals while up there killing 2 birds with one stone as they say.