Going to Hong Kong not only allows you to activate the Hong Kong card
but also enables several functions of the Chinese version of the Apple Watch
1: High blood pressure notifications
2: Sleep apnea notifications
3: ECG electrocardiogram
4: Atrial fibrillation history/abnormal mobile pulse rate reminders
Once activated, it is valid for a lifetime
Specifically, when you arrive in Hong Kong with IP+roaming status
Iphone Health APP→Profile→Health Check List→Activate the above notifications once
Permanently usable after returning to the mainland ​​​