3M radial plastic abrasive discs work with an electric hand drill and feature embedded cubitron mineral. As the wheel wears, fresh abrasive is exposed. Discs are tough and long lasting. Discs and 1/4" mandrels are sold separately. The 3M990 mandrel holds up to 16 discs and covers widths from 1/8" - 1/2". The VLR991 mandrel holds 15 - 28 discs and covers widths from 9/16" - 1-3/16".