Polar Electro POLAR M21 User Manual page 25

5. You can now start warmup with your Polar Heart Rate
Monitor.
Quick start: In the Time of day display, press and
hold START/STOP/OK for a couple of seconds.
To stop the heart rate measurement:
Press START/STOP/OK to stop the stopwatch. If you
want to QUIT the heart rate measurement mode,
press SCROLL UP or SCROLL DOWN to enter
the Time of day display.
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