The device is designed to turn on and off lighting devices. When the illumination falls below a certain value (threshold threshold) and after the set delay has elapsed, the relay includes its contacts. This is indicated by the on / off LEDs – green and relay – red. When the illumination is above a certain value (threshold threshold), the action is inverse. The illumination is measured by a light sensor that is mounted so that no direct light on the illuminators is on it.