Chengdu, Chengdu, ductile iron manhole cover cast iron covers anti-settlement covers Chengdu Chengdu covers manhole covers with higher ductile iron ball, clear sand processing technology products implemented in accordance with national requirements of the standard, painted galvanized corrosion, rust asphalt paint, neat appearance, beautiful, suitable for urban road reconstruction covers replacement product has the following five anti-function: anti-settling, anti-displacement, noise, anti-theft, anti-bounce.