The Simon 50e series includes a complete set of electronic detection and control devices necessary for a smart home system. It includes a time-delay switch, a sound-light sensor switch, a high-sensitivity PIR sensor, a footlight with PIR sensor, a dimmer, and an all-in-one thermostat. All of them are designed with the same principle of a pure square geometry for the background and round shapes for the functional units. This logical and intuitive interface design achieves a good balance between unobtrusive appearance and ease of recognition. The six devices share many common parts behind the different look in order to reduce the overall production cost.