World-1st GSM 900 Cellular Phone Signal Repeater Booster + Antenna (55dB) Frequency range: Up link GSM 890-915 Downlink GSM 925-960 Gain(dB) GSM Up link: 55 GSM Downlink: 60 Gain adjustable range: MGC30dB Guard band rejection: GSM(BW-60dB)42 &lt;br&gt;MHz (BW-70dB)45 MHz