Glossary/Collet

Collet

Close-up of a collet in situ on the balance staff with hairspring

The collet is used to fix the innermost coil of the hairspring to the balance staff. In the image, we can see the hairspring neatly inserted into the gold thing in the center; that gold thing is called the collet,, while the silver protrusion in the center of the collet is the balance staff.