24" X 12" Steel Return Air Filter Grille for 1" Filter - Removable Frame - * Filter Included * [Outer Dimensions: 26 5/8" X 14 5/8"] 6" Round Duct Pipe Actual Filter Size – 13 18" Round Duct Pipe Fixed 45 horizontal blades LO1810

Actual Filter Size – 13 3/4"w x 31 3/4" x 1"

including the ability to mount without removing the thermostat when using the ring base

+ Product Details Size – 10"w X 16"h is the size for the duct opening measurement only

4" X 14" Is The Size For The Duct Opening (floor/vent hole) Measurement Only

Actual Filter Size – 19 3/4"w x 23 3/4" x 1"

24" X 12" Steel Return Air Filter Grille for 1" Filter Removable Frame * Filter Included * [Outer Dimensions: 26 5 8" X 14 5 8"] 6" Round Duct Pipe Actual Filter Size – 13 18" Round Duct Pipe Fixed 45 horizontal blades LO1810 Actual Filter Size – 13 3 4"w x 31 3 4" x 1" including the ability to mount without removing the thermostat when using the ring base