Apple reveals Apple Watch Series 6 with blood oxygen sensor and a more affordable Apple Watch SE - Tech Guide
How to use the Blood Oxygen app on Apple Watch - Apple Support
Apple Watch Series 6 blood oxygen monitoring: how does it work and how to use it? - PhoneArena
Amazon.com: Apple Watch Series 7 [GPS 41mm] Smart Watch w/ (Product) RED Aluminum Case with (Product) RED Sport Band. Fitness Tracker, Blood Oxygen & ECG Apps, Always-On Retina Display, Water Resistant :
Apple Watch 6's blood oxygen sensor is unreliable and misleading - The Washington Post