18" X 24" Steel Return Air Filter Grille for 1" Filter - Removable Frame - * Filter Included * [Outer Dimensions: 20 5/8" X 26 5/8"] 8" Diameter Actual Filter Size – 35

Actual Filter Size – 35 3/4"w x 21 3/4" x 1"

The vent also has a bug screen to eliminate pest intrusion

Tamper-Proof Security – Features a robust design to prevent unauthorized access and protect your thermostat settings

875" width X 16" height

+ Product Details Perfect Fit & Easy Sizing - Designed for a 10" x 20" duct opening (measured at the opening)

18" X 24" Steel Return Air Filter Grille for 1" Filter - Removable Frame - * Filter Included * [Outer Dimensions: 20 5/8" X 26 5/8"] 8" Diameter Actual Filter Size – 35+ Product Details Size 18"w X 24"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 20 5 8" width X 26 5 8" height Actual Filter Size 17 3 4"w x 23 3 4" x 1" High Quality High quality solid stamped steel with counter sunk screw holes (screws included) and no sharp edges Installation Location Sidewall and ceiling Design Removable door face for easy filter change & cleaning uses a 1" thick filter.