The X-LOCK R574 Best for Metal Fibre Disc ensures high stock removal. Its tough zirconia grain achieves high stock removal in coarser grits and good surface quality in finer grits. The disc's thick and vulcanised backing supports a stable grinding process. Use this disc on mild steel, cast iron, non-ferrous metals and aluminium Changing fibre discs is fast and convenient thanks to the keyless X-LOCK system. Discs are suitable for clamping on an X-Lock or standard rubber backing pad. X-LOCK sanding discs also fit standard angle grinders.