Various
The ultimate manhole covers site
Standard of the Ecuadorian Institute of Standardization - Instituto Ecuatoriano de Normalización (INEN)
Standard 2499 is a standard for cast iron

The standard released to the public by INEN (in Spanish) https://ia600405.us.archive.org/6/items/ec.nte.2499.2009/ec.nte.2499.2009.pdf

An example of a cover that carries the standard on the "ultimate manhole covers" site. From this lid the picture that appears in the general section was taken.
There are 6 manhole covers in the site that has this standard
Click for all the covers with this standard

Click for the rest of the standards in the site

The ultimate manhole covers site

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