Watchmakers create all kinds of mechanical and electronic watches with the utmost precision. For example, they insert movements into cases, affix dials and attach straps. When making mechanical watches, they install barrels, check wheel mechanisms, assemble automatic winding mechanisms and insert crystals into bezels. After completing the assembly they set the watch going and check that it works properly. Most of the work is done using traditional hand tools, but modern devices and measuring instruments are also used. They master the necessary processes: they file, drill, mill and turn minute parts, cut threads and polish surfaces. This ensures they comply with the tolerances of the industry.