... ) Passed ISO9001 Ventilation Fittings for Air Duct Material: Galvanized Steel Pipe Coupling(quick coupling,tube fittings)1. Material: Galvanized Steel Panel ... , Stainless steel sheet is available2. Feature:It used to connect the end of duct, and has exactly pathway and easy ... ,200,250,320,400,500,630,800 and so on. Pipe Coupling(quick coupling,tube fittings)