With the A / B BOX you choose to which source / exit it will go
the guitar signal.
It has one input and two outputs of the signal.
By selecting one output the Led is green,
while the second option is red.
It can also be used inversely.
That is, putting two guitars and one output of the sound.
The power supply is via a 9V Boss type DC adapter.
Because the circuit is Passive the pedal can be used without power supply
(But without lighting the Led)
Dimensions: 11cm x 6cm x 3.2cm
Price: 50 Euro