The Garmin HRM-Tri is a heart rate monitor designed for triathletes and other multi-sport athletes. It is worn around the chest and uses ANT+ and Bluetooth technology to transmit heart rate data to compatible devices. The HRM-Tri is also designed to be comfortable and unobtrusive during physical activity, with soft, rounded edges and a compact size. In addition to heart rate monitoring, the HRM-Tri also tracks other metrics such as running dynamics, cadence, and ground contact time. It is also water-resistant and can be used during swimming. Overall, the Garmin HRM-Tri is a high-quality heart rate monitor that provides a range of useful data for athletes looking to track their performance during multi-sport activities.