The Master Flow 14 in. x 6 in. x 8 in. Universal Register Box creates a straight in-line transition from round pipe or insulated flexible duct to an air register or grille. It can be installed with sheet metal screws. It is suitable for most HVAC applications. This universal register box is made of galvanized steel.Galvanized steel constructionCreates a straight in-line transition from 8 in. round pipe or insulated flexible duct to a 14 in. x 6 in. air register or grilleInstall with sheet metal screws not includedAlways seal seams with building code-approved sealant or duct tape not includedAlways insulate ductwork for greater system efficiency and comfort insulation not included