The manufacturer’s covers are made of metal or metal and concrete , and their shape is square or rectangular . No colored or gilded covers were found for this manufacturer. City emblems also do not appear on the manufacturer’s covers.
Usually, the purpose of the cover is not indicated on it; in some cases it can be inferred from the cover itself (drainage covers or from the name of the consumer on the cover ).
The year of manufacture of the cover usually does not appear.
Standards The European standard EN1433 and its related load classes appear on some covers, with the most common load class being D400 .
Typical Covers Many covers are made of concrete, with a metal frame (often decorated) . Many drainage covers with diagonal slots were also found . Another type features a matrix of squares with short lines in between .
Many covers are diagonal (square or rectangular, composed of two triangles, with opening done by lifting one of the triangles ).