There's two kinds -- the Kal@ and the Kam0a. The Kam0a is more "acoustic," but though it's tuned like a bass, the octave is that of a guitar, so you are loosing low end in exchange for the more acoustic quality. The Kal@ uses these rubberized strings so it actually is tuned AND in the same octave as a regular bass. BUT, not as acoustic. I've actually picked up a Kam0a but not the Kal@, which is the one I'm going to look at today.
The reasons I want one of these things are: they are extremely portable, like put it in the overhead bin portable, and I travel a lot, and I've always wanted a portable bass instrument that I could bring with me and play. My Fender is BIG and very heavy. Also, I have little tiny hands, which have always been a handicap with my bass-playing -- trying to get back into shape but it's hard, and it would be a lot of fun to have something small and manageable like one of these.
But, which one?
The obvious answer is, I NEED BOTH!!!
Er, but even one will have to wait.