They are working good so far. We are getting these at the office I work at. They are made well and the price is better than other brands I have purchased.
I purchased two of the Merv 11 filters, as I have split units between upstairs and downstairs. Both filter whistle while the units are running. Six one of the units is right behind your head as a watching TV you can imagine it gets kind of annoying. other than that theyre good filters made of high-quality materials and they should serve their purpose.