Quite possibly the most buggy product Apple ever made, and expensive, too.
It was 1992, and no one made an ergronomic ADB keyboard, nor was there proof that ergonomic keyboards actually prevented repetitive stress injuries (RSI). For about $200, the Apple Adjustable Keyboard was to solve these problems.
The keyboard, beige in color, consists of a total of seven (yes, SEVEN) parts. A standard ADB cable connects the keyboard to the computer. The keyboard itself is a single part, with two palmrests, that may be detached. A short ADB cable connects the keyboard with the number/arrow/function keypad, which has it's own palmrest. Try managing all that on the average desktop.
The keyboard itself is split in the center, so that the angle of the two halves to each other may be adjusted. This is the one good feature of the keyboard, as there is no proof that ergonomic keyboards are any better, only that it is better to change the position of one's hands, which this allows. Many commonly used keys are placed on the number keypad - all of the function keys, the number pad, and the arrow keys. The keyboard does have a power button on it, as well as volume adjustment, and a mute button. The function keys are not normal keys, but buttons like those used to adjust the volume - they just don't feel right.
The keyboard is generally unreliable and it just doesn't feel right to type with. In addition, as someone who holds the keyboard on his lap while typing, the short ADB cable connecting the number pad is just too short. For the cost, new, it just wasn't worth it. Now, it is a choice one might want to consider - complete keyboards are available on eBay for US$20-30 - just be sure that they guarantee no DOA - it might be worth trying.
<grumble>Why can't someone just make a nice clickey keyboard with a power key on it?</grumble>