A handy series of grits to remove high spots and even out gouges before polishing. Made with ruby abrasives, the stones in these assortments are extremely hard and have an extra coarse grit to remove material faster than standard polishing stones. Use them to flatten your surface enough to begin polishing after. Pair them with a compatible holder (sold separately) to use them by hand or in power tools. Though not required, you can add a water-soluble or oil-based lubricant to keep debris from building up.