- Specifically designed for triathletes- Our smallest and lightest heart rate monitor (HRM)- Comfortable, easily adjustable strap- Stores and forwards heart rate data to Forerunner® 920XTEnhance your triathlon experience by pairing HRM-Tri with your Forerunner® 920XT. The HRM-Tri stores heart rate data when underwater, then forwards it to the 920XT. Our smallest and lightest module fits within the width of the strap. Its soft, rounded edges and covered seams make the strap super-comfortable out of the water, too.