“Where are the [pulse oximeter] sensors in it?”
Uh...that was answered back in #257. You’re going in circles.
BTW: I’ve worked in the blood testing industry (embedded SW engineer). Measuring O2 isn’t hard.
You’re really working hard at making yourself sound like an idiot.
Then you should know that this crappy watch will give you crappy readings from its blood oximeter. Apple knows this and is working on it. Otherwise it would be an included feature NOW
Just by the nature of the contact area, this watch will never give good blood oxy readings