shank-mounted flap wheels

shank-mounted flap wheels), which are abrasive tools used for sanding, deburring, and finishing. They consist of multiple "flaps" of sandpaper or abrasive cloth radiating from a central core.
​Common Uses
​Contour Sanding: Because the flaps are flexible, they can conform to irregular shapes, curved surfaces, and the inside of pipes better than a solid grinding stone.
​Metal Finishing: Often used to remove rust, scale, or light oxidation and to create a uniform "brushed" finish on metal parts.
​Woodworking: Useful for sanding down carvings or deep grooves without flat-spotting the material.
​Deburring: Removing the sharp edges (burrs) left behind after cutting or drilling metal