It's never been possible to record heart rate accurately during swimming - it is nowThe swim stores up to 20 hours of heart rate data during swims, then forwards it to a compatible device at the end of the sessionIt also sends real-time heart rate to the watch when the monitor is out of the waterHRM-Tri strap is the smallest and lightest heart rate monitor from GarminDesigned with rounded edges and no exposed seams, the strap remains comfortable during extended hours of training, and is designed to be worn under a tri suitA simple bi-fold adjustment reduces elastic weight and makes sizing easyAdditionally, the new straps provide advanced run metrics - by measuring cadence, vertical oscillation and ground contact time when paired with a compatible deviceLasts up to 18 months (assuming three hours/week use) with user-replaceable CR2032 batteryHRM-Swim has the same features as HRM-Tri with a special non slip design - keeping the monitor in place - even during push-offs from pool wallsBundle version includes one of each strap