Garmin HRM-Tri Heart Rate Monitor Heart Rate Monitors : Specifically designed for triathletes, the Garmin HRM-Tri Heart Rate monitor is Garmins smallest and lightest yet. This comfortable chest strap is easily adjustable for bike rides, runs, and open water swims. Soft, rounded edges and covered seams give your skin the smooth fit it deserves. Stores and forwards heart rate data to the Garmin ForerunnerA(R) 920XT. Battery life: 10 months (Tri training 1 hour-per-day). Withstands pressures equivalent to a depth of 50 meters. Supports heart rate variability and advanced heart rate features. Provides swim interval heart rate statistics.