20"w X 20"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: 21.125" X 21.125"] w24h24 Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 16" X 4" duct openings

Actual Filter Size – 21 3/4"w x 35 3/4" x 1"

+ Product Details Size - 10"w X 20"h X 2"d (for duct opening measurement only)

+ Product Details Size - 16"w X 8"h is the size for the duct opening measurement only

20"w X 20"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: 21.125" X 21.125"] w24h24 Ideal for Walls & Ceilings:+ Product Details Size 20"w X 20"h Is The Size For The Duct Opening Only, Dimensions With Outer End are 21. 125" X 21. 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