Train even better with heart rate by pairing HRM-Swim with Forerunner 920XT. The durable, non-slip strap keeps the heart rate monitor in place, even during wall push-offs. Sleek design causes minimal drag and stores heart rate data as you swim. Out of water, real-time heart rate, interval summaries and stored heart rate are transmitted to the 920XT. Stores up to 20 hours of heart rate data. Designed for all swim environments -fresh water, salt water and pools.