IMPRESSIVE FINISH ON METALX-LOCK R444 Expert for Metal Fibre Disc produces an impressive finish on metal surfaces- Aluminium oxide grain is particularly suited for work on metal applications- Fully synthetic resin bonding on vulcanised fibre backing gives high work stability and optimal sanding results- Keyless X-LOCK system for fast and convenient disc changes; suitable for clamping on X-LOCK/standard rubber backing padChanging 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.