Classic recessed switch with black porcelain frame and black porcelain knob in a design that was common in Europe during the first half of the 20th century.

This switch has a so-called staircase function, which means that it can be used as a regular switch to turn a light source on and off. It can also be used in rooms, corridors or staircases to switch on a light source at one end of the room and off at the other end. If staircase switching is required, two switches with staircase function are needed. If a light source is also to be controlled from a third switch, this must have a cross function.