SIZE & COMPATIBILITY – The size of stack boot angle is 12” x 3.25” x 6", galvanized sheet metal floor boot 90 is compatible with duct 6" SUPERIOR QUALITY – Our L boot stack angle is made of high-quality galvanized sheet metal with crimped ends (snap-lock design) for easy fitting and secure connection to consecutive duct joints USE OF L BOOT – The Boot stack Angle used for right-angle transition from round pipe or insulated flexible duct to a register or grille. It can also be used with metal risers PRACTICAL DESIGN – The product is designed to convert ductwork into a vent to heat a room. In a home, the trunk of the HVAC system either runs through the ceiling or the basement of the home