The set consists of 5 pieces: a stamped steel 0-4-0 mechanical steam engine, a coal tender, a hopper car, a boxcar, and a caboose. All of the cars have 4 metal wheels on metal axles and have those upward pointing tab and slot couplers on them that Unique is known for. The set is used and the cars show some playwear but are very presentable. I tested out the engine, and it runs fine - I posted a short video of my bench test of the engine.
An interesting conversation piece, as Unique really didn't make that many different trains. In fact, the legend is that when they did come out with these trains, the toy king Louis Marx answered with his 7 inch line of lithographed trains to compete with, and later eliminate, Unique as a competitor in the toy train market! Great for the layout or around the tree at Christmastime, or perhaps to add to your collection of Marx! Photos show all of the items from all 6 sides. Also added a closeup of the underside of the engine, so you can see the windup motor better. Yes, the key IS included on this one.