DIMENSION - Fits a DUCT SIZE opening of: 6" x 18". The Overall size of the flush mount register INCLUDING the frame is: 8 and 3/4" x 21". Flush-mount vent sits flush with 3/4" hardwood floor. The frame is tongue and groove structure for easy installation. PREMIUM MATERIAL - Made of Unfinished Solid Red Oak wood, Select Grade Wood DESIGN - Flush Mount with frame; Slotted Wood Design floor vent, Horizontal slots for maximum strength APPLICATION - Wall registers; Wood registers; Air registers; Heat registers; Register covers; Ceiling Registers MADE IN THE USA ON CAPE COD MADE IN THE USA ON CAPE COD! Cape Cod Air Grilles serves contractors and homeowners across the continental United States and abroad. Our grilles, also known as vents or registers, are available in a wide variety of PREMIUM solid hardwood species and in all standard grille sizes. We take pride in the fine craftsmanship of each grille. All of our products are manufactured right on site on Cape Cod by our woodworking professionals.