The covers in Rotterdam are usually made of metal

 

and are square

 

, rectangular

 

, or round

 

in shape.
In some cases, when round covers are intended for sidewalks, they are surrounded by a square frame, which greatly facilitates the paving work around them

 

No colored covers were found in the city; on the site, one gilded cover appears (information - "Stumbling Stones")

 

.
The city emblem does not appear on the covers.

Usually, it is not possible to determine the purpose of the cover, except for drainage covers

 

or those used for information

 

.

No covers unique to the city were found, and they are generally typical of the various manufacturers.

Manufacturers
The covers on the site were made by the Dutch manufacturer TBS SOEST bv

 

or the Austrian Wallner Neubert

 

.

Standards
The common standards are the European standard EN124

 

, accompanied by a load class (D400)

 

. In addition, the Austrian ÖNORM standard

 

and the Austrian B5110

 

can also be found.