Sait zirconia belts use a Zirconia Alumina abrasive on a H (medium) weight polyester backing. Zirconia Sanding Belts have a zirconia grain, which lasts considerably longer and cuts more quickly than aluminium oxide. This is due to its self-sharpening grain which does not dull as quickly.Due to the very aggressive and fast-cutting nature of the grain, zirconia is generally only available in the coarse to medium grit range (often no finer than P120), any finer than this and the belt is entirely aluminium oxide.