duct silencer/duct mufflerSize:80mm-1600mm Material:Stainless steel Galvanized steel Yuyao East ventilation Engineering Company Limited is specialized in producing spiral pipe(Sprial ducts) and accessories manufacturers.(Beijing 2008 Olympic Games spiral pipe product supply). We have the most advanced companies Switzerland SPIRO full metal spiral duct and accessories production lines Products are widely used in air conditioning, airports, shipbuilding, exhibition, Coliseum .,etd