There is elegance in simplicity, and few things are as elegantly simple as a reed switch. The technology is basic and time-tested, and has not changed much in the seven decades it’s been around. But, because of their versatility, product designers are continually finding new uses for the tiny devices. And that’s one reason why these millimeter-sized devices are sold by the hundreds of millions each year. Two other important reasons: reed switches have extremely long life compared to other electromechanical switching technologies and they don’t corrode, despite often being asked to go into harsh environments.