I had been looking for one of these for the last FIVE YEARS. I finally got one (that I could afford)!
As the name implies, it's a Mateba auto-revolver. It's the "safe queen" of my collection of oddities from the firearms world. It's also a variant of the revolver Togusa (I think that's the characters name) carries in the anime "Ghost In The Shell". (his model never really existed)
It's in .357 magnum with a 6" barrel.
If you're interested in buying one, keep an eye on gun auction websites. I got mine on gunbroker.com, but there are others.