Your cellphone often sits in your pocket. It's not visible, and even when it is, they can't tell if you have a medical tracking app installed. A wristband is a

Your cellphone often sits in your pocket. It's not visible, and even when it is, they can't tell if you have a medical tracking app installed. A wristband is always on you, visible, can survive weeks without charge (if they use bluetooth LE and don't have a display) and is impossible to hide.