40" x 16" Aluminum Spiral Duct Air Vent Grille Cover - Fully Adjustable Double Deflection HVAC Air Supply [Outer Dimensions: 42w X 18"h] ceiling + Product Details Size -

+ Product Details Size - 4"w X 34"h is the size for the duct opening measurement only

Powder-Coat Finish – Never rust

actual front end outer dimensions are approximately 27 5/8" width X 36 5/8" height

adds an extra layer of protection

Actual Filter Size – 17 3/4"w x 31 3/4" x 1"

40" x 16" Aluminum Spiral Duct Air Vent Grille Cover - Fully Adjustable Double Deflection HVAC Air Supply [Outer Dimensions: 42w X 18"h] ceiling + Product Details Size -40"w X 16"h Is The Size For The Duct Opening Measurement Only, Actual Front End Outer Dimensions Are 42" Width X 18" 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