18"w X 18"h Extruded Aluminum Adjustable Surface 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"] 8" Diameter Actual Filter Size – 23

Actual Filter Size – 23 3/4"w x 25 3/4" x 1"

+ Product Details Perfect Fit & Easy Sizing - Designed for a 36" x 20" OR 20" x 36" duct opening (measured at the opening)

back blades made of black plastic for reduced air noise and discreet appearance

making maintenance quick and hassle-free

+ Product Details Size - 6"w X 26"h X 2"d (for duct opening measurement only)

18"w X 18"h Extruded Aluminum Adjustable Surface 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"] 8" Diameter Actual Filter Size – 23+ Product Details Size 16"w X 16"h Is The Size For The Duct Opening Only, Dimensions With Outer End are 17. 125" X 17. 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