air ventilation duct 1 Material:FRP,stainless steel 2 low noise, ... intensity,and strength, The FRP ,flexible duct,duct,air conditioning duct, air duct,air ductingBrief introductionIt selects the non-combustible inorganic fiber glass ... galvanized steel ducts,its anti-corrosion is better,its service life is as 3-4 times as steel plate's 3 ...