Apple starts preorders for Watch Series 12, Ultra 4 with new Health Sensing System

Apple launched the Watch Series 12 and Ultra 4, both powered by the new S11 chip and a “Health Sensing System” that delivers the most accurate wearable heart-rate tracking. The system uses a ring of redesigned photodiodes, larger electrodes, and bigger, more efficient green LEDs to record heart rate every five seconds and provide higher-frequency HRV data, viewable via a dedicated watch-face complication.