People arriving in Hong Kong must wear tracking bracelets for 2 weeks or face jail time. Here's how they work.

· In Hong Kong, anyone arriving from a foreign country is required to wear a wristband and follow a 14 day quarantine.
· Some of the devices are small wristbands with a QR code, which wearers are supposed to use to check in with an app on their phones.
· Recently, some arrivals have been given larger bracelets capable of...