You turn on and off (close and open) a switch from your mobile. You can program schedules, days of the week and an external contact (NA), such as a rain detector. It has a pulse mode (NA or NC from 1 sec. to 10 min.) for, for example: opening gates and triggering sirens. From the factory (before configuring), it is in timer mode that also works by detecting changes in the contact input. When it goes from closed to open or from open to closed, the switch changes state. In this way it can be connected to an existing light key and command it either manually or remotely.