Overview
- Apple has begun shipping the Series 12 and Ultra 4, and reviewers published hands-on coverage on Sept. 18–19 that confirmed the watches use a new S11 chip and an upgraded Health Sensing System.
- The Health Sensing System samples heart rate about every five seconds and measures heart rate variability as often as every five minutes to support new recovery metrics.
- A Readiness score combines recent activity, vitals, and sleep to recommend rest or effort and requires roughly seven nights of wear to produce an initial, useful baseline.
- The Series 12 keeps the same external design, returns ceramic finishes, adds Ceramic Shield 2 on aluminum models, comes in 42mm and 46mm sizes starting at $399, and charges faster with the included new charger.
- The Ultra 4 shares many health features with Series 12 but keeps a clear role for endurance users with up to 50 hours of normal use, extended low-power modes, an Action button, satellite messaging, and software features like Audio Intelligence arriving later this year.