The large cones fit into a split-tapered mandrel #M20. The small cones fit onto a threaded mandrel #M100. They are all quick and easy to change, and the wrapped-paper design exposes new grit as the cones wear down.
3M's Ceramic Purple Abrasives are excellent for sanding and finishing wood, metals and other materials. This Cubitron ceramic aluminum oxide mineral sharpens itself with use.