ZW44 Wylde Overdrive - MXR - Max Guitar – Max Guitar
MXR ZW-44 Zakk Wylde Overdrive Pedal - YouTube
The MXR classic overdrive pedal has a hidden switch inside that changes to the Zakk Wylde overdrive. I've seen people mod their own switch for it, but I just drilled a hole
MXR Classic Overdrive - Flip a Switch to Make It a Zakk Wylde ZW44! : 5 Steps - Instructables