A straight register boot or PH1  is a major component of an excellent ductwork system. The boot can be fastened to other ducts, including ceiling and wall units, using a nail and screw. Expect to spend about 20 minutes or less installing register boots. Airtight gaskets in the products reduce and eliminate leaks in heating, ventilation and air conditioning (HVAC) systems. These leak stoppages save you money and lower energy consumption. Straight collars and wider and narrower straight boots can be used to meet your HVAC design needs. Narrower boots start at 8-5″ with wider boots going up to 14 inches.