OWC Ministack 0TB HDD Enclosure. Comes with box, power adapter and USB-B to USB-A cable.
This was bought to stack with a Mac Mini and another one of these (also available for sale) but I never got around to setting it up.
In good condition - there's some scratches on the top plastic which I've tried to show in the picture and a chip in the black paint at the rear of the device (in the last picture).
Any questions, please ask.