COMPACT AND COMFORTABLE – HRM-Tri is the smallest and lightest heart rate monitor from Garmin. Designed with rounded edges and no exposed seams, the strap remains comfortable during extended hours of training. SWIM HEART RATE1 – Stores up to 20 hours of heart rate data during swims, then forwards it to a compatible device at the end of the session.
https://www.amazon.com/Garmin-HRM-Tri-Heart-Rate-Monitor/dp/B012H8IPQS

