Design is not the only crucial factor to consider when selecting luminaires. It is equally important that the system as a whole – light source, optics, reflectors and any operating devices used – should work efficiently. Durability is assured by materials such as aluminium and high-quality coatings. At the same time, repairs should be possible and easy to perform. Precisely fitting enclosures prevent valuable light being absorbed by dirt and dust. Reliability is certified by marks of conformity such as “VDE”, “GS” and “ENEC”.