| | [* black] Scraping the bottom of the ~~barrel~~ watch case, we find the pulse-pounding sensor action. And lenses. |
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| | [* black] Apple's heart rate monitor is actually a [http://en.wikipedia.org/wiki/Plethysmograph|plethysmograph|new_window=true]—it [https://support.apple.com/en-us/HT204666|looks and acts like a pulse oximeter|new_window=true], but Apple isn’t claiming it can measure your blood oxygen level. Why? ''Beats us''. |
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| | [* icon_note] Our best guesses involve [http://appletoolbox.com/2014/06/apple-fda-discussed-fda-regulations-regarding-possible-new-mobile-products-sensors-glucometer/|FDA|new_window=true] [http://www.fda.gov/RegulatoryInformation/Guidances/ucm341718.htm|regulations|new_window=true]. |
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| | [* black] Nestled in the case we also find a magnet, to help seat the watch on its inductive charger. ''Electrifying.'' |
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