The Polar AXN300 will help you keep track of your runs with the Slope counter, check your pace down the mountain or up the rock with the Vertical speed feature, and the barometer allows you to track the changing weather. The OwnIndex® feature tests your fitness level, so you can set a baseline and track your improvements. The OwnCal® feature monitors your energy expenditure (calories) so you know when to refuel your body.Polar exercise featuresWireless ECG accurate heart rate.