18"w X 18"h Extruded Aluminum Adjustable Core Mount Supply Ceiling HVAC Air Grille – Interchangeable: 1-Way, 2-Way, 3-Way or 4-Way - Vent Duct Cover [Outer Dimensions: 19.125" X 19.125"] return grille Horizontal performance assures confident use

Horizontal performance assures confident use of cooling temperature differential of 30 degrees Fahrenheit and greater

+ How To Measure A Grille

Aluminum Garage Door Air Vent Grille Register - With Damper Control Lever For Winter & Summer Settings - With Insect Net Prevent Guard [17

+ Product Details Size - 24"w X 8"h is the size for the duct opening measurement only

18"w X 18"h Extruded Aluminum Adjustable Core Mount Supply Ceiling HVAC Air Grille – Interchangeable: 1-Way, 2-Way, 3-Way or 4-Way - Vent Duct Cover [Outer Dimensions: 19.125" X 19.125"] return grille Horizontal performance assures confident use+ Product Details Size 18"w X 18"h Is The Size For The Duct Opening Only, Dimensions With Outer End are 19. 125" X 19. 125". Design Re configurable Interchangeable Sections Easily convertible into 1 Way, 2 Way, 3 Way, or 4 Way Just lift sections and rotate to re configure direction. High Quality Aluminum The premium durable aluminum will never rust and it will never wear through leaving the material with an elegant, beautiful, and smooth surface, adds