The MDS-S100-120V is a door-activated power controller that turns your lights on and off automatically. It uses a low-voltage magnetic reed switch that recesses into the door and frame. When the door opens or closes, the switch signals the controller, which turns the connected lighting on or off. Easy to install, the MDS-S100 offers a simple, hands-free way to control lighting in closets, cabinets, and entryways.