Early last year, Apple made the bold, court-mandated decision to remove the blood-oxygen feature from the Apple Watch Series 9 and Ultra 2 in the U.S. over a patent dispute with medical technology company Masimo. Since then, all new watches (including the Series 10, which launched several months later) have shipped with the sensor disabled, eliminating a feature available since the Series 6.

Now, Apple has re-enabled the blood oxygen feature for Apple Watch Series 9, Series 10, and Ultra 2 users. In a press release titled, “An update on Blood Oxygen for Apple Watch in the U.S.,” Apple says, “Users with these models in the U.S. who currently do not have the Blood Oxygen feature will have access to the redesigned Blood Oxygen feature by updating their paired iPhone to iOS 18.6.1 and their Apple Watch to watchOS 11.6.1.”

Apple says the update, which arrived Thursday, was enabled by a recent U.S. Customs ruling. To apply the update, open Settings on your iPhone and go to General > Software Updates and follow the prompts. After your iPhone has updates, open the Watch app on your iPhone and select General > Software Update, then follow the instructions to update your Apple Watch.

The new feature will now measure and calculate sensor data on the paired iPhone, and results can be viewed in the Respiratory section of the Health app. Previously, users could take a blood oxygen measurement at any time with the Blood Oxygen app as well as track occasional background measurements. It’s not clear whether this update will take away the ability to take instant readings on the watch.

Older watches that still have the blood-oxygen feature enabled will not be affected by the update, Apple says.