Apple on Thursday re-enabled blood oxygen measurement on Apple Watch Series 9, Series 10 and Apple Watch Ultra 2 models sold in the United States, releasing iOS 18.6.1 and watchOS 11.6.1 to deliver the change. The update brings a “redesigned” version of the feature that had been absent from recently shipped devices after a patent dispute. Under the new approach, the watch’s sensors capture data while an iPhone running iOS 18.6.1 performs the calculations and displays results in the Health app, rather than on the watch face itself. Apple said the design was cleared in a recent U.S. Customs ruling. The workaround follows an 18-month import ban imposed by the U.S. International Trade Commission, which found that Apple’s original on-device implementation infringed patents held by medical-device maker Masimo. Apple had removed the capability from U.S. units shipped after January 2024 while it appealed the decision. Masimo shares fell roughly 4.5% after Apple’s announcement. Watches sold before the ban or outside the United States are unaffected, and Apple has not indicated when the revised feature might appear in future developer betas.