Volatile Corrosion Inhibiting (VCI) Bag is the core technical product of Suzhou Keysun Company, and has passed the testing of Chinese Academy of Sciences, Wuhan Research Institute of Materials Protection and SGS, etc. It is a kind of corrosion inhibiting film produced in the co-extrusion method. When Keysun VCI film or VCI bag is used in the metal product packaging, volatile corrosion inhibitor gasifies in the constrained space and agglomerates on the metal surface, including holes, hollows, gaps and other inaccessible surfaces, forms a gas-phase protective layer, so as to prevent the metal products from corrosion. It is in compliance with the National Standard of the People's Republic of China, American Mi litary Standard MILB22019C and MILB22020C.