30" X 20"opening dimension (vent opening) - actual total grille size is approx 1.5" wider - SEE BELOW HOW TO MEASURE A GRILLEHVAC Premium has been providing superior in quality service for many many years. Our products are second to none, and we?ve helped numerous contractors, DIY projects, and home improvement remodeling specialists complete their masterpiece. If you are looking for a top of the line unit to enhance your project look no further than HVAC Premium. We have the largest selection of Grilles Registers & Diffusers. 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 your air system. These grilles and registers give you an extra measure of quality that you can point out to your family members and house guests. Some of our best features aren?t readily apparent, but you?ll appreciate the benefits over a long period of time. This grille has a high standard of design, production and finish on all products.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 +1.5"".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 our100% money back guarantee no questions asked. ClickAdd to Cart Now! and enjoy a new updated refreshing look to your home."