Introduction - If you have any usage issues, please Google them yourself
Achieve inter-corridor lighting control convenience, a lamp, upstairs and downstairs each have a (closed) switch. Switch is closed does not directly determine the bright lights off, change the switching state is the key to determine the lamp on or off. That no matter how the current state of the two switches, as long as there is a switch status change sound, will make playing in the bright lights off or switch between the two states.