10" x 36" or 36" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 38.5"] Compatible with Duct 10" + Product Details Size – 14" Round Duct Pipe FR M 414 White For 10 duct opening

+ Product Details Size – 8"w X 14"h is the size for the duct opening measurement only

Actual Filter Size – 11 3/4"w x 27 3/4" x 1"

+ Product Details Size – 29"w X 22"h is the size for the duct opening measurement only

Lock and Key included

+ Product Details Size – 16"w X 18"h is the size for the duct opening measurement only

10" x 36" or 36" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum White [Outer Dimensions: 12.5" X 38.5"] Compatible with Duct 10" + Product Details Size – 14" Round Duct Pipe FR M 414 White For 10 duct opening + Product Details Size – 8"w X 14"h is the size for the duct opening measurement only Actual Filter Size – 11 3 4"w x 27 3 4" x 1"