The 200-Series Handheld Remotes are multi-purpose handheld transmitters, designed for emergency signaling, and the remote control of electronic devices. Each transmitter sends a specially coded digital signal on 315MHz to a 200-Series receiver. The one button model is powered by a standard 9-volt battery (not included) and include a belt clip. The four button model uses a single 12-volt battery (not included) and includes a key chain ring.