The Milescraft Insert System for use with a router is one of the few inexpensive ways to make relatively complex inserts in wood with a fairly mechanized process, i.e. easier than making it entirely from hand to do. The 1/8 inch spiral cutter works well but is brittle. When handling and using, care must be taken not to stress it or break it. It can also take a long time to clean the earphone jack with a 1/8" bit.