The Cel-Fi Duo+ Smart Signal Booster for Verizon or T-Mobile by Nextivity is part of the next generation of intelligent signal boosters. With up to +100 dB gain of amplification, it greatly enhances 3G & 4G LTE cell service for all your wireless devices (smartphones, notebooks, hotspots, etc.) on Verizon or T-Mobile for any home or office up to 15,000 sq ft. This two-piece wireless system features the Network Unit (NU) and Coverage Unit (CU). The NU pulls in signal and the CU broadcasts the amplified signal throughout the home. No wires and easy set-up.