#6 tomae is glue mounted to a painted waterproof wooden dia. Although on the Bench Page it is a razor quality very finely gritted stone. I have honed several razors and can report that it is silky smooth and fast cutting. This and a few other bench stones came to me from Mori Toishi Co. in Nagoya. Their family in the Meiji, Taisho and Showa eras owned awasedo and coarser stone arato mines in the northern section of Kyoto.
What we call a tomae is the type of stone, they can be green or a light blue/gray like this one is. Super smooth with no inclusions it can finish razors to shave ready keeness, or knives and plane/tool  edges to razor keeness. The length is unusually long at 210mm x 80mm wide by 11 to 18mm thick from side to side.
Purchase includes a tested tomonagura slurry stone.