Performance Cel-Fi DUO+ improves 3G/4G/ LTE cellular service by eliminating dead zones and dropped calls. With up to 100dB of gain, it will improve cellular service and reduce your cell phone's power requirements to extend its battery life. The Cel-Fi DUO+ covers up to 15,000 sq. ft. (approximately 1,400 m2) of indoor space per system. It's fully self-contained and self-configuring, requiring no external antennas or wiring. Simply plug it in to boost indoor cellular coverage. Cel-Fi DUO+ is available in multiple configurations for use in The Americas, with FCC and Industry Canada approvals.