It is a heart monitor you wear for at least a week that tracks your heart rate and any unusual events. I've had one after a heart attack scare. The monitor comes off after a week or so and you mail it in to be analyzed, along with a log book you are supposed to be writing in any time you have an event, which requires you to push the button on the chest monitor. This usually requires followup with a cardiologist who might run other tests. Nobody gets one of these casually. If he was really sick and needed a monitor like this, the doctor's instructions are usually to go about daily life but to NOT workout until they have made their assessment and cleared you for strenuous physical activity. Also I do not have to point out that none of the above treatment options are in any way cheap or free.