... external,durable ,lownoise,energy saving.applies for factories ,office,storage,dining room,the kitchen,basement to ventilate , exchange air and cool down.The ... .63501350FA-606001706002202.7501350FTA-606001706003801.1501350FTA-757502658503801.350900 ventilation fan /solid and durable/energy saving/for exhaust air for industrial places