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This watch is equipped with Seiko’s unique mechanism “Spring Drive”, and provides the following features.

Spring Drive

Spring Drive, the unique mechanism made available only by Seiko technology, achieves a high precision comparable to that of a quartz watch while using the unwinding power of the mainspring as its sole power source.

Self-winding mechanism
How to wind the mainspring:

This is a mechanism that uses the natural motion of your arm as the power source to wind the mainspring to power the watch.

This is a mechanism that enables you to wind the mainspring by turning the crown by hand to power the watch. This function is convenient especially for winding the mainspring when you start using the watch.

Power reserve indicator
Power reserve indicator:

The power reserve indicator shows the winding state of mainspring (continuous operating time).
The watch keeps working for approximately 72 hours (approximately three days) with its mainspring in fully wound state.

Glide motion:

The seconds hand of the watch moves around the dial in a perfectly smooth movement.

Function and Performance

Time difference adjustment function
(5R66 only) Time difference adjustment function:

When you move to a location having different time zone, you can easily set the watch to indicate the local time.


This watch is powered by the mainspring. To ensure constant operation of the watch, be sure to wind up the mainspring sufficiently before the power reserve indicator points to “0.”
The watch may stop if the power reserve indicator is showing less than one-sixth, especially it is left under a temperature below 0 °C.