1. Our manhole covers include ductile iron manhole cover and gray iron manhole cover, but we can also use other materials according to customer needs. 3. Ductile iron manhole cover adopts a retractable design to enhance the applicability of the manhole cover and can better adapt to the needs of different environments. 3. The surface treatment of ductile iron manhole cover is carried out through powder spraying, anodizing, electroplating, hot-dip galvanizing and other methods, thereby improving the corrosion resistance and aesthetics of the manhole cover.