Your oscillating or rotating multi-tool doesn't do much without multi-tool accessories. Usually, some sanding, sawing, grinding, and milling attachments are already included with your Dremel, Fein, or Bosch multi-tool and you can get started right away. But if you want to expand for specific jobs or just because you like a lot of choice, a set with multi-tool accessories is a good addition. Some sets are specially formulated for certain applications, such as laying floors, polishing, or window renovation.