sewer air fillter, locateted at sewer,can refine the smelly air, very appropriate for the heat wheather of Arabic countries Weight:13kg1.Product unit: made of by polymer composites and glass fiber,aging-resisting,acid -resisting and alkali-resisting , non-corrosion,non-degradable in one hundred years.2.easy installation__Modular components permit easy assembly into existing manholes.no operation, ...