Their site doesn't want to load this morning, but I know what you're talking about. It's made for the kit pen turners who, for the most part anyway, can't turn metals because all they have are wood lathes. I have not used this material (I can turn the real metal mokume) so I don't know exactly what it is made of. Personally I doubt there is much metal in it, or if there is it is in the form of powder held in a polymer matrix. That's the only way you could turn it on a wood lathe with hand held chisels.
If you go to on line places like ebay and etsy and search for "mokume gane" you will find along with true fused metals other listings for things made from polymer clay. There is no metal in the stuff that I know of, just metallic colored plastics. They advertise this stuff as mokume gane, not "polymer clay that resembles mokume gane", so a lot of people who are unfamiliar with the real "wood grain METAL" think it's the read deal.
About 20 years ago when I was starting to work with damascus steel more often, Tim Zowada suggested I make my own to understand how some patterns were made. He said to buy Play Doh. I got some blue and some yellow, rolled them out on the kitchen counter top with a rolling pin, layered them up and rolled them again. I then cut some grooves across my "billet" and rolled it again. I made ladder pattern "doh-mascus"! That's what these people are doing with their polymer clay, and I bet the pen blanks are similar, just not in blue and yellow.
While this material works on the cheaper kit based pens, it is something I would never use on a knife. The real stuff is easy enough to obtain and work.
David