Like this thread if you think the built-in OHRS is not accurate enough!
Hi not sure
https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-265-series/362213/heartrate-so-inaccurate-that-my-watch-is-basically-useless-for-training?pifragment-1279=15#pifragment-1279=16
