Garmin watch forerunner 235 wrist based hrm black red 010 03717 71 forerunner 235 uses garmin elevate heart rate technology an optical sensor measures heart rate 247 at the wrist giving you the option to run without a strap its colourful gauge identifies your heart rate zone and beats per minute in real time no two runners are the same and neither are their goals set yourself up to reach yours by downloading advanced workouts and training plans to your watch from garmin connect you can