12" X 12" Aluminum Insulated Fire Resistant Access Panel Door For Wall / Ceiling Application (Lock and Key) With Frame - [Outer Dimensions: 13" Width X 13" Height] 6" Diameter + Product Details Size -

+ Product Details Size - 20"w X 20"h is the size for the duct opening measurement only

Whether it's a 45° or 95° degree angle

Actual Front End Outer Dimensions Are 12" Width X 6" Height - SEE IN DESCRIPTION HOW TO MEASURE A GRILLE

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 24" OR 24" x 20" duct opening (measured at the opening)

+ Product Spec Sheet

12" X 12" Aluminum Insulated Fire Resistant Access Panel Door For Wall / Ceiling Application (Lock and Key) With Frame - [Outer Dimensions: 13" Width X 13" Height] 6" Diameter + Product Details Size -+ Product Details Size 12" X 12" is the size for the drywall opening measurement only, actual front end outer dimensions are 13" width X 13" height High Quality Strong and sturdy aluminum built to last. Design Aluminum material & color to give your space an attractive look & provide high durability corrosion protection no rust. Built in tumbler lock and key is provided Easy Access Provides easy access for HVAC, plumbing, electrical, crawlspace etc.