Red Bar?

I'm sure there is an obvious answer but what is the red bar that goes around the watch face on the left hand side of the screen? Sometimes it's there and sometimes it isn't. I've read the manual but I've drawn a blank. Any ideas?

Thanks in advance.

It's your "move bar" to let you know you're inactive. It triggers every hour that you're not moving around. The 1st solid half represents 1 hour and the segments following that are additional 15 min increments up to the 2 hour point. You have to start walking around to clear it. You can turn the move bar off completely in your watch settings, temporarily by putting the watch in do not disturb mode, and it won't trigger during the hours you've set as normal sleep times. If yours keeps going off, it's time to get up off your ass and do something. :D LOL

LOL, thanks for the reply. So that's what it's for!

Those long meetings at work are to blame!!