The fixture is designed based on the principle of a reflective three-shade system, which directs the majority of the light downwards. The shades are made of mouth-blown opal three-layer glass, which is glossy on top and sandblasted matt on the underside, giving a soft and diffuse light distribution.
Poul Henningsen designed the three-shade system back in 1925-1926. The first lights using the system were designed by PH in cooperation with Louis Poulsen for an exhibition in Paris. This partnership continued right up until his death in 1967.