Get a bargain on the 20" x 20" Stamped Face Filter Grille, 4" Housing in soft white (Shoemaker FG4-20X20) via PlumbersStock. This FG4 series stamped face filter grille has louvers with 1/2-inch spacing. The filter housing accommodates filters that are a whopping 4 inches thick. It's got a hinge that opens parallel to the longest side. It's 2-way or 4-way reversible, depending on if it's rectangular or square, respectively. It's easy to access and clean. The filter retention tabs hold it into place. Shoemaker has made a name for itself by manufacturing reliable heating and cooling products.