The Morley ABY Selector / Combiner Switch lets you switch between two inputs to one output (e.g. two guitars in to one amp), or one input to two outputs (e.g. one guitar in to two amps). The footswitches allow you to choose between the A or B channels, or have A and B on together. The pedal is passive and can switch between channels with no power requirements, however if you want to take advantage of the LED channel indicators you will need to use either a 9V battery or power adapter, there is a quick clip batter door on the rear allowing easy battery installation.