Fiberglass files are used by hand (most often in holders) as well as in ultrasonic polishing systems and are very good for lapping and polishing. These files can be used in conjunction with diamond pastes. Fiberglass files have very good tensile strength and flexibility, which guarantees excellent results in hard-to-reach places such as cross-sections, ribs and bridges, cavities, etc. You can grind these files, so they are easy to shape (for example, you can thin them, sand to the tip and other shapes). They are also characterized by a long service life.