Garmin’s HRM-Tri heart rate monitor strap is fashioned from a soft material and well-suited to tracking heart rate on land or during wetsuit-legal events, but we don’t recommend it for pool workouts or swims without wetsuits. It runs on a standard CR2032 battery with a claimed battery life of 10 months at an average of one hour of training per day, and it transmits wirelessly to a Garmin Epix, Fenix 3, or Forerunner 920XT device.