The Fitbit Charge 6, the latest addition to Fitbit's lineup of fitness trackers, has introduced a significant advancement in health monitoring with its built-in blood oxygen saturation (SpO2) feature.

Charge 6 is Fitbit's flagship fitness tracker band. The follow-up from Charge 5 features some tweaks under the hood, but little in the way of design changes. To the untrained eye, they look the same.

Fitbit and Xiaomi have been in the fitness tracker war for nearly a decade, so it's fitting that the new Xiaomi Mi Smart Band 8 Global Edition and Fitbit Charge 6 should launch in the same week. These ...