This looks like some windowless container ranging from one to eight 5' cubes in size. There is a locked door on it. On the inside of the container there are rooms with a total volume of 200 5' cubes. At the center of the main room, there is a cylinder surrounded by control panels. The Box can manufacture keys to unlock the door to its entrance; it may create up to one key every 24 hours. The control panels can be used to transport the Box of Holding and Traveling to any place and time on the same plane, provided that you make sufficiently good Knowledge (Arcana) checks.