... air duct Light weight Oil,Acid,Alkai&high temperature resistant&fire-retardant PVC Good price,fine quality,satisfying service Air duct/ Air ... laboratory ,air-conditioner,engine room, the municipal conduct engineering,fire-fighting to ventilate or exhaust waste air,dust to supply ... effectively during working.with the strap or pp rope can conveniently connect to the portable ventilator to use together.