Natural whetstone, origin unknown, is an Ao-to (blue whetstone). The shape is not perfect, but it should still be usable. We recommend this for those who can make some adjustments themselves. There is a crack on the whetstone surface. There are also cracks and chips overall, so it has been treated with cashew lacquer. As it is a natural product, there may be streaks or areas that drag during sharpening that were not apparent when we tested it. Please consider this as well before purchasing. Length: Max 208mm Width: Max 54mm Height: Max 34mm