For professional use the finer the grit, the denser the material, which leads to a finer finish of the surface of the tool. Finer grits cut slower because they remove less material. Grits are often given as a number, which indicates the density of the particles with a higher number denoting higher density and therefore smaller particles. Dimensions of the stone (inches): 8 1/2" x 2 1/4" x 3 1/4"material: Artificial stone origin: Japan grit: Ara-to,1200 (coarse).