Garmin vivosmart 4 Activity Tracker + Heart Rate Black 010-01995-10 - Best Buy
User manual Garmin vívosmart HR+ (English - 16 pages)
The validity of activity trackers is affected by walking speed: the criterion validity of Garmin Vivosmart® HR and StepWatch™ 3 for measuring steps at various walking speeds under controlled conditions [PeerJ]
vívosmart® HR/HR+
vívosmart® HR/HR+ Owner's Manual
Garmin vivosmart HR Manual
Hands-on: Garmin's new Fenix3 HR with optical HR, new Fenix3 bands, major software update | DC Rainmaker