Huami only unveiled the Zepp Z in the middle of November, but it turns out that there is a second version of it. The second model includes an ECG monitor and an NFC module, which were both missing from the Zepp Z that Huami announced internationally.
https://www.notebookcheck.net/Zepp-Z-Huami-has-also-released-an-ECG-and-NFC-version-of-its-new-smartwatch.506802.0.html