Shapton Glass Stones are known for their exceptional quality, durability and ease of use. Unlike other waterstones, Shapton Glass Stones do not need to be soaked in water before use - simply wet the surface and begin honing your blade. Shapton sharpening stones are made with finely graded ceramic cutting media that requires less flattening and lasts 4-5 times longer than most water stones. The abrasives in Shapton Glass Stones are also extremely uniform, meaning the abrasive encountered with the first pass of a blade will be the same as the 5000th pass. Each stone is comprised of a 5mm tempered glass backing plate fused to a 5mm thick stone. The #30000 grit stone has a particle size of 0.49 microns and is ideal for putting an ultra sharp edge on a straight razor. Although it's not an essential stone, we do recommend using it after the #16000 grit stone if you like a really sharp edge. We recommend using the Shapton Stone Holder to hold the stone in place when in use. Made in Japan.