I have this lovely little bout, about 18 x 84 or so and it is so great that I would love to know what it is so I could look for a larger version. It is the fastest stone I have and is also smooth with great feedback. I have been using it to deal with specific parts of blades that are giving me problems, but if I had a 40 x 175 piece of this I would be in honing nirvana. Any ideas what it could be? Are these piccies good enough? A signature feature, I think, are those little lenses in the side, they are about the same color as the slate it is glued to. Thanks for helping.