2. Pressure resistance: cast iron manhole cover is better than composite manhole cover; Note: Although the composite manhole cover can meet the standard, the broken cast iron manhole cover has never been seen on the road, and the composite manhole cover is often broken.
3. anti-theft: the composite manhole cover is cheap and almost no one steals it. (that is, the cost is low and there is no recycling value)
4. Weight: the composite manhole cover is light in weight;