Polar's RS300X is a sports watch and heart rate monitor in one. The watch monitors your heart rate through it's included sensor and chest strap and records your speed and distance. The RS300X is designed for recreational athletes who require all essential heart rate and timing features. The RS300X is also compatible with Polar's S1 foot pod to monitor cadence, G1 GPS Sensor to track your location, and the FlowLink to sync your data to your computer.