Nothing wrong with these valves, they work perfectly fine & the ones I received were in good order, I did feel that they had been hanging around for sometime & therefore they could be described as shop soiled. The advantage is that they are made properly with real shafts & bushes & butterfly flaps that shut correctly. The disadvantage is the size of the assembles you need a fair amount of space to fit them in & they will need supporting because of the weight, the other problem is finding brackets man enough to do the job, I ended up buying modern flimsy brackets & reinforcing them. For my money the extra hassle was well worth the trouble, the end result of building a custom made exhaust/ ventilation system with quality components was money well spent.