registers, grilles and diffusers for air distribution systems; manual air volume dampers; control grids and baffles for use with registers, grilles and diffusers for air distribution systems; air conditioning and furnace accessories, namely, baseboard and floor registers, side wall registers, ventilating registers, ceiling diffusers, and perimeter diffusers; commercial registers and grilles used in heating and air conditioning systems; dampers; damper kits comprising damper bearings, counterweights, chain, chain coupling and chain lock; damper regulators and regulator sets comprising chain, pulleys, hooks and screws packaged together; gas vent pipes and chimneys; flexible duct primarily of nonmetal for use with air distribution systems; and metal air duct fittings for use with air distribution systems