This is a complete 14"X24" HVAC return air filter grille kit. This kit includes one 14"X24" filter grille, one 14"X24" 26 gauge  galvanized metal filter box 5" deep with 3/4" flange, one 12" dovetail collar 4" long, one 14"x24"x 1" Merv-11 filter and 4 mounting screws. The 12" collar hole will be cut centered in the metal box for you to install the 12" dovetail collar. Connect this kit to your return ductwork with your provided metal pipe or 12" flex. Outside dimensions of the filter grille is 16 5/8"x26 5/8". Please check out our store and our other ductwork. We specialize in fabricating the highest quality ductwork available with the quickest turnaround time in the industry. Our goal is to make the installation of your HVAC equipment as easy as possible. We do this by providing you with the best price, products, and customer service you  expect and deserve. We are always here to help until your project is completed and you're completely satisfied.