XH LCD GSM 900Mhz Cell Phone Signal Repeater Booster Amplifier + Yagi Antenna High gain, easy installation and operation. Full-duplex, single-port design. ALC technology, adjust extent automatically Big linear power, control intermodulation & scatteration stablyCompatibility of electromagnetism according with ETS300 609-4 LCD Light Working & Signal Condition Indicators Note: before bid, please make sure your SIM card support GSM 900MHZ, if not support, this item can not working.