Simple to install into any type of round ductwork, these cast aluminum access ports allow for quick and easy inspections, cleaning, and other maintenance of the ducting line. Ideal for use in spiral pipe installations where the duct cannot be easily removed (i.e. if the duct is screwed, riveted, or welded in place). Fittings are labeled according to the pipe diameter they are built to install onto i.e. a 4" Clean-Out will fit piping that measures 4" in diameter.