Super rare developers 64DD system. It has a lovely blue fascia, instead of the normal black one.
Very nice condition. A few scuffs, no doubt from being shoved in the closet by the developer that owned it. "Stupid thing!" they probably said, "You cost us a mint! Screw Nintendo, and screw you!". Or maybe not.
In any case it's impossibly rare. This unit includes only the system and one blue developers rewritable disk. No other cables are needed with this system, just like a regular 64DD. Note: It doesn't do much without a developers cartridge, and apparently Nintendo recalled them all.