Ideal for individuals who work in a noisy environment or who may not hear the ringing of a standard telephone due to hearing loss. The CL 11 is simply plugged in between the telephone and the telephone socket and is ready to use immediately. The CL 11 draws its power from the telephone socket, so the device does not need to be powered by batteries or connected to the mains. The connections are RJ plugs. The additional ringer is easily connected between your phone and the telephone socket, providing an extra signal for incoming calls. The included cable for the CL 11 additional ringer is approximately 48 cm long.