Polar F4 Heart Rate Monitor - Features and BenefitsTarget Zone Indicator --Indicates when you are above, below, or within your heart rate target range.Heart Rates--Records average and maximum heart rate for workout. Calories Burned--Polar's OwnCal technology measures the number of calories you use during your workout. Key SpecsTime of Day --Stopwatch--Receiver Water Resistant: Up to 30 Meters