#How can you tell if a watch is precise?

The watch is accurate if the time is adjusted on a regular basis so that it roughly coincides with the radio station's time signal.

The watch's time initially agrees with the radio station's time signal, however there is a daily error after operating. Then comes the cumulative growth, although the daily increase in error value is constant. This watch qualifies as well if the trip time error figure is within the watch's quality level. In order to increase accuracy, you can move the speed needle if the error value is more than the defined standard.

#Why do cases made of 100% steel occasionally contain rust spots?

All steel watches won't rust, in general, but everything is relative. The variety of stainless steel is enormous....