12" X 12" Steel Access Panel Removable Door For Wall / Ceiling Application (Lock and Key) With Frame - [Outer Dimensions: 13" Width X 13" Height] 12" Diameter + Product Details Size - 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size - 24"w X 10"h X 2"d (for duct opening measurement only)

Actual Filter Size – 21 3/4"w x 13 3/4" x 1"

+ Product Details Size – 14"w X 16"h is the size for the duct opening measurement only

Optional Butterfly Damper Available At Asin: B007CNEL1W

+ Product Details Size - 22"w X 34"h is the size for the duct opening measurement only

12" X 12" Steel Access Panel Removable Door For Wall Ceiling Application (Lock and Key) With Frame [Outer Dimensions: 13" Width X 13" Height] 12" Diameter + Product Details Size 4 X 12 Is CRFG2028 Width_14in + Product Details Size 24"w X 10"h X 2"d (for duct opening measurement only) Actual Filter Size – 21 3 4"w x 13 3 4" x 1"