#20 Nakayama kiita mounted on wooden dai.
Although not very attractive, this an excellent stone for knives, and maybe some razors. Nakayama stones have a reputation for being universially fine, it is my finding that this stone will match well with harder steels than with softer. 
It has the classic Nakayama straight namazu filled yellow streek of alternate minerals, and a swath of darker red & black goma particles seen as a "wave" in the center. These alternate minerals do not themselves do not affect the steels of a knife in any way, but it is because of these I have discounted this stone.
I found the stone extremely good for knives like this classic Masamoto seen in the photos.
The painted lacquer dai is glued to the stone, it looks very fresh and is in excellent condition.