Smart Level Security comes with a super tiny penny-sized optical sensor. Featured with Plug and Play smart design, Smart Level Security automatically detects the water level status when mounted. Magnetically-coupled sensor makes it easy to adjust to the desired level to secure your aquarium. Maintenance is also as simple as you can imagine. It is able to prevent your aquarium from overflowing or running dry. When the level status changes, Smart Level Security will shut down the device immediately.