HRM-Tri is designed for running, biking and open water swimming. Enhance your triathlon experience by pairing HRM-Tri with Forerunner 920XT. Stores heart rate data when underwater, then forwards it to the 920XT. Garmin's smallest and lightest module fits within the width of the strap. Soft, rounded edges and covered seams make the strap super-comfortable out of the water too. Ideal for race use when used under a wetsuit.