Keeley DD-3 Mod

This is a rare Boss DD-3 modded by Keeley Electronics.  For a brief description of the mod:

There are two parts to Robert Keeley's mod of the Boss DD-3 digital delay pedal. First, he adds switchable analog feel to this industry-standard compact delay by incorporating two different smoothing capacitors. Use the small three-way switch to select between these caps or the original stock sound of the DD-3.

The second mod takes the DD-3's direct out and turns it into an effects loop, allowing you to add any external effect just to the DD-3's repeats. Add slight chorus or phase to the signal to simulate tape effects, or experiment to find whatever your imagination wants!

Also with a quick search you can find the PDF manual that goes into more detail (I couldn't post the link here).

Great pedal, especially using different effects in the loop.  If you have any questions don't hesitate to ask.