The GRE Super Amplifier™ is designed to amplify signal reception from 100 MHz to 1 GHz. The gain is controlled with a control knob on the amplifier, which is adjustable from 0-20 dB for fine tuning signals to attain clear and stronger reception levels. The Super Amp is equipped with BNC connectors on each end to make the connection to your radio simple. This preamp features a bypass switch which enables you to return to normal scanning by simply turning OFF the amplifier. In the bypass mode there is no loss in gain. Works with most standard handheld or base scanners. Requires a 9 volt battery (not supplied) that provides about 21 hours of use.