EKG accurate heart rate during exercise. Large, easy-to-read display. Target zone alarm. Recovery heart rate timer. Calorie counter tracks calories burned during exercise. Displays heart rate in beats per minute or percent of maximum. Automatic activity timer keeps track of exercise time. Recalls time in target zone, activity time, and average and peak heart rate. Comfortable, lightweight transmitter with owner-replaceable battery. Elastic strap fits chest sizes from 25 inches to 53 inches. Water-resistant. 30m INDIGLO night-light backlight. Watch with 12/24 hour time and month/date display. 2 year average battery life. One year warranty.