Polyfoam Washable Filter is a medium efficiency filter suitable for ventilation and air conditioning systems, where cleanability is required rather than a disposable cell. These filters are initially more expensive than disposable panels. Use of washable filters makes it unnecessary to have valuable space-consuming spares on the premises and also obviates the need for frequent ordering of replacements. This is reticulated polyurethane foam, enclosed within an aluminum channel frame with a galvanized retaining mesh on the outlet face. The frame is provided with corner gussets to provide added rigidity.