Operating without any external energy source, Factem's Sound Power Telephone is dedicated to locations that are difficult to access, inhospitable or even dangerous. Organized in a network, these products make a simple and effective communication system in all situations where voice transmission is essential and access to a power source not possible. The range consists of Sound Power intercom units, headphones, and handsets. A wide range of accessories are also available to complete the features of this unique communication system.