4" x 36" Return Air Grille - Sidewall and Cieling - HVAC Vent Duct Cover Diffuser - [White] 4"w X 36"h Is The Size For The Duct Opening Measurement Only, Actual Front End Outer Dimensions Are 5.75" Width X 37.75" Height - SEE IN DESCRIPTION HOW TO MEASURE A GRILLE PROPERLY Why HVAC Premium? You may think of grilles and registers as a generic component of the ventilation system in your house. But they are also the most visible representation of you air system. With HVAC Premium you get an extra measure of quality that will be visible to your family members and house guests. Every part is hand inspected for quality before it is packaged, no exceptions. No Sharp Surface Edges. Just run your finger along the edge of the top plate and you will find a smooth finished surface. Heavy Gauge Steel. Heavier gauge than needed, built for durability and long life in mind, but still light and handy. Powder-Coat Finish - Smooth, Shiny, Scratch-Resistant, Beautiful. Looks Like It Was Just Waxed How To Measure A Grille Overall Size: Measure the size of the air duct/drywall opening. Do not measure the overall size of the register itself, only measure the "hole" in the wall/duct. Every grille has a front end frame, that will overlap at wall joint. Total outer size of this grille is; listed size +1.75". Width vs Height The first number in a grille size, represents the width, the second number represents the height. Example: If your hole is 20" wide by 14" tall, order a 20x14. If your hole is 14" wide by 20" tall, order a 14x20. 100% Satisfaction Guaranteed Don’t worry, you're covered by our 100% Money Back Guarantee, no questions asked. Click Add to Cart now & enjoy a new updated refreshing look of your room.