40"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 41.25"W x 5.25"H] with filter Its generous size and universal 75 Width X 17 LO3634 w20h20

Its generous size and universal design ensure a perfect fit for a wide range of thermostat models

+ Product Details Perfect Fit & Easy Sizing - Designed for a 16" x 25" OR 25" X 16" duct opening (measured at the opening)

rated at R3

Do not measure the overall size of the access panel itself

+ Product Details Size - 36"w X 10"h is the size for the duct opening measurement only

40"W X 4"H [Duct Opening] Linear Aluminum Clip On Bar Return Air Grille [Outer Dimensions: 41.25"W x 5.25"H] with filter Its generous size and universal 75 Width X 17 LO3634 w20h20 Its generous size and universal design ensure a perfect fit for a wide range of thermostat models + Product Details Perfect Fit & Easy Sizing Designed for a 16" x 25" OR 25" X 16" duct opening (measured at the opening)