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

+ Product Details Size - 26"w X 16"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 28 5/8" width X 14 5/8" height

Actual Filter Size – 31 3/4"w x 35 3/4" x 1"

Noise free components - no vibrating louvers etc

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