The fast cutting 100 mesh Ripple Disc™ brand diamond disc cuts like a 40 mesh and the 180 mesh disc cuts like a 60 mesh. The Ripple Disc™ brand disc is excellent for rough cabbing and preforming large faceted stones. As the tips of the ripple forms wear, fresh diamond is exposed, permitting the disc to remain sharp throughout its long life. This disc will cut agate with ease. 1/2" Arbor hole.