Incabloc shock protection system
The Incabloc shock protection system is the trade name for a spring-loaded mounting system for the jewel bearings that support the balance wheel in a mechanical watch, to protect the wheel's delicate pivots from damage in the event of physical shock, such as if the watch is dropped. == History == The Incabloc system was invented in 1934 by Swiss engineers Georges Braunschweig and Fritz Marti, at Universal Escapements, Ltd, of La Chaux-de-Fonds, Switzerland.
Source: Wikipedia — Incabloc shock protection system (CC BY-SA 4.0)