Surface-mounted spring-loaded double dimmer in black porcelain with brass knob, a design that was common in Europe during the first half of the 20th century.

The double dimmer has a so-called crown function, which means that it is used to dim two separate light sources. The supplied dimmer switch is placed in appliance boxes in the wall.

For surface mounting on wood paneling or other flammable material, an insulating plastic base plate should be used as additional fire protection.