The Faithfull FAI11512M Cut Off Disc is a very fast cutting disc that must never be used for grinding. This power tool accessory would be used mostly by trade professionals. Depending how you use it, it's important to choose either the metal or stone cutting disc. It must be placed at a 90 degrees angle against the workpiece. For your safety, it is important to ensure that the disc is properly mounted. Supplied as a single unit.