Aluminum alloy impeller with sound-absorbing housing and square integral frame; high efficiency, low noise, smooth operation, and easy installation. Wall exhaust for industrial, civil, gymnasium, and entertainment venue applications. Aluminum alloy weatherproof louver (or self-weight gravity louver) to prevent rain and natural wind backflow. Single-phase motor (<0.55kw) or three-phase motor available; rubber or cork padding between fan and wal optional. Corrosion-resistant and explosion-proof versions available; housing material: carbon steel,stainless steel, or FRP.