British designed and built specifically for UK digital TV. This amplifier has the lowest noise figures in its class. Pulls in weak signals for steady picture and clear sound when lesser mastheads cannot. 10 - 20dB variable gain means that you can adjust the amount of gain you require. This item can be powered from the vision 5v power supply or any 12v power supply without performance degradation. All vision mastheads come with adjustment tool which adjusts the gain and tightens the F connectors.