Pedal known and present a

I note that I have no problems of "POC" as mentioned below

works well to switch between two amps, or even switch between two guitars into one amp

ie, it is reversible, as in / out
In addition, you can switch A or B, as well as A + B
pedal very handy for all sorts of uses
even on stage, if you have no tuner pedal that allows you to AB and moved him to send the signal to your tuner usual