Antichocs devices are shock absorbers that are found on the balance axis to prevent the pivots of this axis from breaking when the watch falls.
Balance axis is for two reasons the most fragile point when a watch receives a shock. A balance wheel must have as much inertia as possible, which also means a high leverage. Also a balance must have a low friction, so to achieve this goal we place very small diameter pivots. Their diameter is about 9 hundredths of a millimeter which is 1.5 times the diameter of a hair. These two parameters make the balance axis the most fragile point of a watch when it is not equipped with anti-shock.
In the past, the way to strengthen this weak point was to have pivots as short as possible. These pivots have always had, and still have, conical bearing pivots that are much stronger than cylindrical ones. These two parameters have always reinforced this delicate point of a watch.
Towards the end of the 18th century the first drop guards on the balance shaft were produced. Some industrial models followed in the 20th century. The principle of these bumpers and shock absorbers is to have a hole that moves at the time of the shock and then returns in place. Apart from a few brands that have developed their own shock absorbers, there are two main ones used by many houses. They are the Incablocs and the KIF.
These very small components are the result of five assembled components. An Incabloc can be recognized from a KIF by the number of contact points between the spring and the upper stone, an Incabloc with two contact points and a KIF with three contact points at this level.