10"W X 20"H [Duct Opening] Steel Air Vent Return Grille - HVAC VENT DUCT COVER DIFFUSER - [Outer Dimensions: 11.75"W X 21.75"H] return filter + Product Details Perfect Fit actual front end outer RG1612AL Compatible with Duct 4"

+ Product Details Perfect Fit & Easy Sizing - Designed for a 26" x 36" OR 36" x 26" duct opening (measured at the opening)

+ Product Details Size – 16" x 16" is the size for the duct opening measurement only

+ Product Details Size - 20"w X 26"h X 2"d (for duct opening measurement only)

this guard ensures long-lasting protection and security

+ Product Details Size – 8"w X 12"h is the size for the duct opening measurement only

10"W X 20"H [Duct Opening] Steel Air Vent Return Grille HVAC VENT DUCT COVER DIFFUSER [Outer Dimensions: 11.75"W X 21.75"H] return filter + Product Details Perfect Fit actual front end outer RG1612AL Compatible with Duct 4" + Product Details Perfect Fit & Easy Sizing Designed for a 26" x 36" OR 36" x 26" duct opening (measured at the opening) + Product Details Size – 16" x 16" is the size for the duct opening measurement only