The watches are also expected to feature upgraded sensors and internal components with improved performance, efficiency, and accuracy. One example that the report gives is a new optical heart rate sensor.
The stainless steel variants of the Watch Series 9 will apparently be manufactured using 3D printers which use less material and are more environmentally friendly. Apple may also use this process for making the cases of the second-generation Ultra starting next year.
The Series 9 will continue to be available in 41-millimeter and 45-millimeter sizes, whereas the Watch Ultra 2 will be available in the current 49-millimeter size. We may see some new colors, including a black option for the Ultra.