As per the previous posts, we have the regular, LX, small PM rackmount, and the big 3phase PX model line. Now we have a few LX super duty units. These single phase LX units are modern and have a built in extended run module attached. They typically provide an hour of runtime even at half load.
They come in a 16kva frame, but can be built as 8, 12, 16 or 16N+1.
The one in the photo is brand new (which wont last long), but the others are late models 08-09 series. I fairly certain they were developed after the original LX line.