Straight Register Boot - 12" X 6" X 8" Round Floor Grille What does this mean

What does this mean

+ Product Details Size - 18"w X 8"h X 2"d (for duct opening measurement only)

Pre-flared ends with nuts are for simple and easy installation

Actual Filter Size – 33 3/4"w x 27 3/4" x 1"

Straight Register Boot - 12" X 6" X 8" Round Floor Grille What does this mean+ Product Details Size & Compatibility The size of galvanized sheet metal straight floor boot is 12" X 6" X 8". It is compatible with 8" duct Superior Quality Made in the USA. Our straight register boot is made of high quality galvanized steel metal for durability and rust prevention. Applications The straight boot is used for the transition from round pipe or insulated flex duct to register or grille + Product Description If you are looking for a