The grey 20-pin wire is used on the Ghost Trap Pedal. The wire connects from the Hammond Plastic 1591L Project Box to the Grey D-Sub Housing across the front of the pedal. It can easily be found on many older computers. The correct one is grey with one red wire on the side. If you have a few old computers laying around, you should have plenty. The correct length is about 6 or 7 inches.