Flap discs are abrasive accessories for angle grinders which are constructed with lots of individual strips (or flaps) of abrasive material arranged on top of each other. As the disc wears down fresh abrasive material is continuously exposed, meaning the discs can be used until they are completely worn out, with little reduction in performance. Flap discs are most commonly used for grinding and sanding applications. Although they are more expensive than standard grinding discs, they confer several advantages: firstly, as they are not prone to bursting they are safer to use. Secondly, they are much more versatile. Although they are primarily used on metal, flap discs can also be used on materials like wood, eg for coarse sanding or shaping tasks. Thirdly, a much finer finish can be achieved when grinding metal than would normally be possible with a standard grinding disc. This means flap discs are often preferred where the final appearance of the workpiece is important, and some of the less aggressive variants can even be used for polishing.