Clarke SDVH5X120C Aluminium Oxide Velcro Disc With 8 Holes is widely used in sanding applications, especially in wood and metalworking. They are designed to attach to a Velcro backing plate of an orbital sander. The 8 holes on the disc serve as dust extraction channels, helping to keep the work area clean and improving the longevity of the sanding disc. The 5-inch size is also a standard measurement for many orbital sanders.