Hole size 22.23mm (7/8") Grit size P120. Applications: Stainless steel Normal steels Alloy steels Non-ferrous metals and their alloys. Flap discs are manufactured in high quality zirconia abrasive. High stock removal on coarse grits, performs well on stainless steel. Zirconia's inherent feature of cooler cutting when grinding makes it a much more durable and hard wearing grain than aluminium oxide and less likely to discolour stainless steel.