Abstract: A dust and water tight electric pressure switch that is highly visible, even in a smoke filled area, includes a lightguide disc disposed between a ring-like cover and a cylindrical housing disposed behind a slightly depressible flexible zone at the center of the disc. The flexible zone covers the open front end of the housing. The disc is constructed of a light-collecting polycarbonate and is formed with relatively small light radiating surface to produce high contrast at the latter. Disposed within the housing is a contactless switch arrangement including a plurality of so-called light barrier units arranged about a light source, and an actuator extending from the rear of the flexible zone. A light shield carried by the actuator controls the amount of light which impinges on the light barrier units as a function of the position of the actuator as determined by how much the flexible zone is depressed.