Both versions were very similar, differing primarily with the addition of adjustable height legs in the AEKII and other minor changes.

The case extended downward to sit on the desk, so it provided considerable internal volume.

The case also had a significant amount of empty space at the rear, behind the top row of keys.

The plastic of the case shell below the keyboard section on top was serrated, a common detail found on many Apple products of the era.

The first working prototype of the Extended Keyboard II was produced at Design ID by Richard Howe, Donal Ryan and John Fitzgerald.