The movement is the caliber 7C21, which is also used in divers' watches.

The battery used is a 10-year battery, and while it retains the retro look from the days of hand-wound watches, the inside has evolved into a high-spec watch.

The railway watches used on Japanese railways boast some of the highest levels of accuracy in the world and can be said to be Japan's most representative working watches.

Why not use a radio-controlled clock movement, which boasts accuracy?

Radio-controlled clocks receive the time at a fixed time every day and display the time accurately down to the second, but they have a weakness and are not used in railway clocks.

Radio-controlled clocks can only receive signals when the clock is stationary, making reception difficult on trains where there is a lot of movement.

The biggest weakness of radio-controlled clocks is their susceptibility to magnetism. Previous railroad clocks used movements from clocks for the blind, but the current 7C21 movement has improved practicality, making them a more practical clock.