Filter Holding Frames and Housings | Standard & Custom | Smith Filters
Amazon.com: Filtration Group 38363 Pad Holding Air Filter Frame, 26 Gauge Galvanized Steel Frame with a 16 Gauge Welded Wire, Gray, 12" Height x 12" Width x 1" Depth (Case of 12) :
Custom Corinthian Vent Cover Return Air Filter Frame (Bronze) - 30" x 24.5" opening size (32.5" x 26.25" overall) no mounting holes, With filter frame - Vent and Cover