This is a Boss SD-2 Dual OverDrive in Excellent Condition.
It allows you to select between “Crunch” and “Lead” sounds.
With independant controls for each channel...
you can set the Volume…Tone…and Drive separately.
Select either…”Crunch” or “Lead”…or set it to switch beck and forth between the two sounds.
It can also be used with a remote footswitch.
Sounds Great and Fully Functional.
Box is included.