Glossary of watchmaking

Inertia block

Masses ou masselottes | 慣性ブロック/カンセイブロック | 惯性块

Inertia block

Small pieces of metal placed on the balance of the watches to regulate variation in rate in the absence of an index, in particular for chronometers.

A small piece of metal whose inertia slows or accelerates the movement of the balance.