The QRM canceller is inserted into the feeder of the antenna from the without any other modifications to the radio. The box has a built-in PTT control to keep the canceller connected during transmission. However, this requires an additional auxiliary receiving antenna, such as a 2m/6.6ft antenna or only a few meters of wire in the shed.The two antennas receive unwanted signals, resulting in different phases.The QRM canceller now allows adjustment of the phase angle and amplification to cancel out unwanted signals before they reach the front end of the receiver It is based on a completely innovative concept and cannot be compared with normal muffler performance.Colour:blackMaterial:Aluminum alloyPackage Contents:1 x QRM Canceller1 x PTT Cable1 x FM Rod Antenna1 x Power Cord3 x F Adapter UHF/SL16-SMAOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.