@beebo
KardiaMobile. https://kardia.com/kardiamobile
Easily acquired on amazon and on their own website. Look for sales, though, and if you have prime, it can help to reduce the costs. Full service requires a paid subscription. The device will still do its job without the subscription.

@beebo
Yes some folks get hooked on it and some find it a useful tool. it's a personal preference.
I always wondered if some of these tracking devices offered a way to track how many heartbeats the old ticker had left how many would use it. with the introduction of the continuous monitoring glucose meters, some who are not even pre diabetic are buying them so they can get ahead of diabetes. Just my opinion but way too much technology out there for the average human.