Product review (5 stars): Excellent Filter
I bought an extra so I could immediately switch them out when cleaning the filter.  It's an excellent wiry barrier between the outdoor and indoor environment and helps keep dust and particles from collecting on the exhaust fan housing and blades.  It's very easy to clean; I just spray the dirt away with warm water, tap off the excess moisture and let it air dry.  Definitely recommend if you have this type of wall exhaust fan.