[jolux]

>Heart rate is simple. How can it mess that up?

You might be surprised: https://www.cnbc.com/2016/05/23/study-shows-fitbit-trackers-...

[loons2]

That story is about Fitbit, which I don't have.

I check my pulse against a stopwatch during the same minute that Chinese no-name is counting my pulse, and the result is the same.