The Inovonics high power repeater intelligently amplifies transmission from any EchoStream series transmitter while ignoring background noise. Therepeater is perfect for large facilities such as multi-floor buildings, multi-building sites, shopping malls, campuses and other open-air installations. Virtually any number of repeaters can be added to a system, scaling the system size as needed. Key Features Includes backup battery No wires or programming needed Self-configuring Case tamper protection Frequency: 902 - 928 MHz North America