14"w x 14"h (Duct opening size) steel filter return grille with removable door for 1-inch filter replacement - Overall dimensions: 16.6"w X 16.6"h •The Listed size 10"x 8"

•The Listed size 10"x 8" is for inside duct opening measurement

3) select the listed size that match the duct opening size

it refers to the size of the "tongue"  so that it will fit in a 8"x8" hole

18" long heavy duty steel construction with white powder coating finish

14"w x 14"h (Duct opening size) steel filter return grille with removable door for 1-inch filter replacement - Overall dimensions: 16.6"w X 16.6"h •The Listed size 10"x 8"The Listed size 14"x14" is for inside duct opening measurement, actual outside dimension is 16. 6"x16. 6" Stamped Face Steel Construction with 1 2" fin spacing for high air flow Screws are included for easy installation White Powder coating with matte finish Individually packed with card board box for ultra protection Size Selection Guide Measure the size of the air duct opening(the size of the hole ). Select the listed size that match the duct