Sangamo Q553 Solar Dials come in 4 variations depending on where you are in the British Isles the switch is adjusted to match the slight differences in sunrise and sunset times. Simply locate where you are on the map and add the number on to the end of the part number or select the equivalent zone. The Solar Time Switch is ideal for applications which require control linked to sunset and sunrise times. Popular applications for solar time switches include street, stairwell and security lighting. Once set, the switches track SUNSET and SUNRISE throughout the year, without the need to sense light levels. This avoids the installation and maintenance problems associated with photo sensing devices and means they can be left to operate unattended for years.