Apple announced the Watch Series 12 and Ultra 4 today. Both include a new "Health Sensing System" and S11 chip that give the devices the “most accurate heart rate sensing in a wearable," Apple claimed during its fall event.
Apple's depiction of the S11 chip.
Credit:
Apple
Both watches will use the new S11 chip alongside the new "Health Sensing System," allowing the watches to deliver higher-frequency heart rate and heart rate variability (HRV) measurements than prior Apple Watches.
The Watch Series 12 and Ultra 4 (pictured) will run watchOS 27.