End register boot or PH3 products are used to transition or connect rectangular and round sheet metal ductwork. For example, you can use an end register boot to connect a round sheet metal pipe to a rectangular wall stack. Whether you are building a brand new structure like a home or office complex or remodeling an existing facility, you can use the products to build out or improve upon existing standard heating, ventilation and air conditioning (HVAC) systems. Products are available in a range of sizes from 8-5″, going up to 14-7″. The durable metal and aluminum products hold up well beneath low to medium pressure.