For all the new health features Apple touted at Monday's iPhone 16 event, one familiar one was missing: blood oxygen. The feature, which Apple introduced along with the Series 6 device last year, will not be included on the Series 10 models sold in the United States. Everywhere else in the world, though, will be able to get the tech on the new watch.

The exclusion of such a key feature as blood oxygen must be a bitter pill for Apple as the company has made health features an intrinsic part of its smart wearable. This feature is, in fact, a product of an ongoing patent battle between Apple and medical device company Masimo. That forced Apple to disable the feature on the Apple Watch Series 9 and Ultra 2 last November.

Apple hasn't said whether the feature's removal is a hardware change on the Series 10, or perhaps simply disabled through the software, as it was on the Series 9. That'll be clearer when the smartwatch goes on sale and teardown experts get to work. If it's a hardware change, then Apple would have had to make slightly different models for each market.

Apple has been fighting Masimo's case since Day 1. After the important ban was reinstated in January following only a reprieve, Apple filed to institute a similar ban against Masimo's Freedom health watch.
On Monday, Apple did roll out new Series 10 health features that will be global in reach, including sleep apnea detection.