metal tubing; pipework of metal; connectors of metal for pipes; grilles of metal; grilles of metal for ventilation openings; ducts of metal, for central heating installations; air-conditioning ducts of metal; metal air-conditioning ducts; ducts of metal for air-conditioning installations; metal expansion joints for piping and ducting; metal vent covers for HVAC ducts; vent covers of metal for HVAC ducts; ventilating ducts of metal; ducts of metal for ventilating installations; pipes and tubes of metal

ventilation dampers; apparatus for ventilation; air vents [ventilation systems]; ventilation installations; apparatus and installations for heating, cooling, steam generating, drying and ventilating; air purifying apparatus