The pendant is easily recognized as a medical device.
First responders are familiar with medical pendants so they will investigate to see what data it holds.
On seeing the QR code the first responders will scan it with their smart phone or smart tablet to gain the information it holds.
The information displayed identifies the person, displays contact details, medication, medical history, allergies and other personal information the wearer wants to share such as their blood group. This information can be edited at any time by the owner of the pendant.