Reinforced concrete single protective airtight door, reinforced concrete movable threshold protective airtight door, damp-proof airtight door, protective door, rubber tube explosion-proof valve, civil air-defense airtight door, civil air-defense door, and other civil air-defense equipment products, are fixed-point production of civil air-defense products set by the National Defense Office, and is currently one of the largest civil air-defense product manufacturers in China.
