Mirka's Progressive Bond technology help make the Royal sandpaper a "state-of-the-art" coated abrasives. Heavy weight backing make Royal great for hand or machine sanding Unmatched load resistance Flexibility like no other; yet tough, with super edge wear Full resin bonding for strength and durability along with a special non-loading stearate. Royal's aluminum oxide abrasive is especially good for for hand sanding in courser grits and the heavy backing.