US Patent 7524362 Modular filter assembly

An air treatment assembly for treating air passing through an air duct comprises a frame defining an interior space and having an inlet opening providing access to the interior space, an air treatment medium sized to be inserted into the interior space through the inlet opening, and a keyed connection between the frame and the air treatment medium to control the engagement of the air treatment medium with the frame. The air treatment assembly also comprises a frame defining an interior space, an air treatment medium sized to be received within the interior space, and an air quality module integrated with the frame.