This 4" round aluminum oxide sharpening stone has both coarse and fine abrasives. The coarse side of this combination India stone is used to sharpen dull edges quickly. The fine side is used to restore slightly dulled cutting edges and enhance the finish left by coarse side. 4" in diameter by 1" thick.
This stone is similar to, but a bit harder and finer grit than, the Norton 4 x 1 Round Combination Crystolon Stone.
Norton Item Number: IB64
Norton Part Number: 61463685545