The Polar RS300X is the perfect training partner. Without knowing your heart rate, you can only get so far. The RS300X combines these three to give you a true understanding of the effort you put in to your workouts. 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. Polar Fitness Test with OwnIndex - a fitness test that measures your aerobic fitness at rest in just five minutes. The result, Polar OwnIndex, predicts your maximal oxygen uptake (VO2max ). With the Polar Fitness Test you can measure your aerobic fitness by yourself, automatically and without any exertion. No other equipment other than a heart rate monitor is needed. Polar OwnZones - Determines personal heart rate limits for a training session. The Polar OwnZone (OZ) feature determines an individual training zone. It guides you through an appropriate warm-up routine and automatically determines a safe and effective training heart rate zone - your OwnZone - while taking into account your current physical condition Recoding Features - this monitor will record heart rate, calorie expenditure, maximum heart