The European regulations governing the production, installation, import and marketing of these products are already in force. A set of data which are useful for identifying the producer, the country of origin, type, class, shape, dimensions etc. should already be provided on the packaging.

The EN 1051-1 standard (in Italy UNI EN 1051-1, in Germany DIN EN 1051-1, etc..) for example, defines the maximum size variation, shape parameters, as well as the classes that the various families of blocks for walls and floors fall under.

It is ESSENTIAL to note that the standard defines/subdivides the blocks into three different “CLASSES” (3 quality levels).
These classes (Class 1, Class 2 and Class 3) are defined on the basis of the maximum size variation allowed for blocks (up to a maximum of 1 mm, over 1 mm and up to a maximum of 1.5 mm, and over 1.5 mm up to a maximum of 2 mm of variation to the nominal size respectively).
SEVES, world leader and specialist in the glass block sector, has always distinguished itself from other producers who operate marginally in this market thanks to the high quality of its products. SEVES Group factories  were the first in the world to obtain the ISO certification as they have always operated in compliance with stricter quality criteria than those laid down in  national standards.

It must be noted here that in using glass blocks, the installation phase is a highly delicate operation on which the quality of the finished product and the speed of execution both depend; in the “dry” laying (wood and metal structures) even the slightest variation or discrepancy in size can jeopardise the final result.
The installation cost is also a relevant factor and it consequently influences the total value of the work to be carried out.
That's why the superior "quality" of the glass blocks with "precise" height and size will allow for state-of-the-art creations (walls, prefabricated panels, etc.), in this way also reducing the installation costs.