Garmin Fenix 3 - [widget] JMG-WGT Zones HR v1.20 (download link below in message) A widget displaying HR in real time with its time in zones. Similar version to the widget https://www.facebook.com/GarminVivoactiveHR/posts/682614281900535,
Garmin heart rate guide: Features, devices and accuracy - Wareable
JMG-WGT Zones & Alert HR | Garmin Connect IQ
Forerunner 230/235 - Viewing the Heart Rate Widget
Garmin heart rate guide: Features, devices and accuracy - Wareable