16" x 3" Aluminum Spiral Duct Air Vent Grille Cover - Fully Adjustable Double Deflection HVAC Air Supply [Outer Dimensions: 18w X 5"h] fixed bar + Product Details Size -

+ Product Details Size - 4"w X 18"h is the size for the duct opening measurement only

Quality Packaging – Carefully shrink wrapped with cardboard backing to prevent damage in shipment

+ Product Details Size – 30"w X 12"h is the size for the duct opening measurement only

+ Product Details Size - 16"w X 32"h is the size for the duct opening measurement only

The total outer size of this grille is the listed size plus 2 and 5/85"

16" x 3" Aluminum Spiral Duct Air Vent Grille Cover - Fully Adjustable Double Deflection HVAC Air Supply [Outer Dimensions: 18w X 5"h] fixed bar + Product Details Size -16"w X 3"h Is The Size For The Duct Opening Measurement Only, Actual Front End Outer Dimensions Are 18" Width X 5" Height SEE IN DESCRIPTION HOW TO MEASURE A GRILLE Installs Directly On Round & Oval Spiral Duct No Frames, Box or Other Attachments Needed Commercial Grade Aluminum Will Never Rust Designed for Warehouses, Factories, Workshops, Gymnasiums & Restaurants Easy Unrestricted Air Flow For Your HVAC System 180 Degrees Double Direction Adjustable