Natural whetstone, Nisshozan Suita (nest board). I surfaced the original stone myself. This is a DIY level job by an amateur, so please refrain from purchasing if you are looking for perfection. There are layer cracks and chips, so areas other than the whetting surface have been treated with cashew lacquer. There are some uneven areas. This is a Suita that produces a lot of mud and has high abrasive power. It is ideal for removing scratches from medium grit stones. It is a very easy-to-sharpen whetstone, so it is also recommended for beginners. The streaks on the whetting surface may catch on some steels, so if you are concerned, please dig them out or avoid using that area. Since this is a natural product, there may be streaks or areas that pull the steel that were not apparent when I tested it. Please consider this when making your purchase. Length: Max. 180mm Width: Max. 64mm Height: Max. 28mm