Shoemaker 950-20X20 20"X20" Adjustable Wall Diffuser Designed to fit 20" x 20" hole, overall size is 22-1/4" Width x 22" Height. Adjustable aluminum airfoil blades with multi-shutter damper. Vertical air deflectors with nylon bushings for easy adjustment and quiet settings. Countersunk mounting holes for flush appearance with color matching Phillips posi-drive screws. All componet parts, rivets, linkage and handle are enclosed in the valve for trouble-free operation.