These were designed by Paul Barth and built around 1960/61. I think people call these the Mk VI. They're not worth the big bucks like the Mk IV and Mk V, but are cool guitars. They're a lot like Rickenbackers from the same era, but cost a whole lot less. It's a cool guitar, enjoy it. You sometimes see them with Barth on the headstock too. If you don't know who he is, look him up... an important missing link in guitar history.
(and if you want to sell it sometime, gimme a shout)