Watch who spends more time writing you "zero" no heart rate rather than give you heart rate. Backgrounds batteries discharged and replaced by me, at my expense, for the same result! A good twenty field tests, chest strap more or less tight, more or less placed low on the chest, nothing works! I specify that this is not my first shows heart and I used to put the strap on the thorax.
All this would be laughable if it was only a watch for a training recovery health concerns. Stay away urgently so I do not even understand that such products can be marketed. My rating is identical to that written me this watch: a big "ZERO" pointed to a potentially dangerous for health!
