Watch Terminology Dictionary

This refers to the running time of the mainspring. As a result of the widespread use of break-resistant mainsprings such as Nivaflex, it has become possible to make the mainspring thicker and longer, which has resulted in a relatively longer power reserve. Nowadays, by adopting multi-barrel (multiple barrels) that efficiently utilize the space in the movement, it is possible to give a long power reserve without increasing the movement diameter. The display of the remaining running time is called a power reserve indicator.