Where there's smoke, there's the potential for danger. Become aware of the potential for fire with the Medallion Series Smoke Detector with Transmitter. When the photocell detector senses the presence of smoke, the built-in transmitter sends a signal to any Medallion Series Mini Receiver. Easy to install in any room, it is powered by a long-life, 3-volt lithium battery for round-the-clock, 24-hour protection.