Speedi-Products EX-DFRP 05 5-Inch Diameter Round Adjustable Plastic Diffuser, White Speedi-Exhaust Products are made in the USA Ideal for exhaust and supply air duct systems and fans. Fits a 5" Duct This plastic round adjustable ceiling diffuser is easy to install using a stainless steel grip clip which provides a snug fit ; Fits size xxx Seal joints with approved duct mastic sealants and tapes Consult your local building codes for approved installation practices