The lid, regardless of size standards, is a type of ductile iron castings. Firstly, it particularly enhances plasticity and toughness. Generally, the material of the lid varies, with the standard size typically being 600MM, and the lid wall thickness being around 13mm or more.

Cast Iron Manhole Covers: Available in various sizes for easy maintenance of different pipelines; specifications and dimensions vary. In the north, due to weather conditions, heavier covers are used: *600D400, 450*750B125, and typically 600mm in size.