Polar RS300X Heart Rate Monitor Automatic or Manual target zone (% / bpm / HRR%) - helps you to set specific targets and aims whilst you excercise Heart Rate - A measurement of the work your heart does, expressed as % of your maximum heart rate. Visual and audible alarm in target zones - A feature informing you every time your heart rate and/or speed/pace exceeds the upper limit or falls below the lower limit of your target zone during a training session. Average Heart Rate of total exercise - A figure expressed in beats per minute (bpm) representing the average heart rate measured over a specific period of time (e.g. a training session). Can also be displayed as BPM. Polar OwnCal - Counts and displays calorie expenditure. The Polar OwnCal feature shows your energy expenditure during one training session as well as your accumulated kilocalories during several training sessions. You can set daily and weekly training goals in terms of calorie expenditure with the OwnCal feature.