The rugged Forerunner 310XT is the triathlete's indispensable training tool a GPS enabled, swim proof trainer that tracks bike and run data and sends it wirelessly to your computer. This multi sport device has up to 20 hours of battery life, tracks distance, pace and heart rate optional, and goes from wrist to bike in seconds. Forerunner 310XT tracks your position precisely with GPS satellite data and records distance, pace, heart rate optional, power data from ANT enabled third party power meters and more. High sensitivity GPS and HotFix satellite prediction mean Forerunner acquires satellites quickly and tracks your movement even near tall buildings or under tree cover. Waterproof to 50M 1000 lap history Multi sport: changes sport mode with the press of a button Create custom, goal oriented workouts Pace alert triggers alarm if you vary from preset pace Timedistance alert triggers alarm when you reach goal Interval exerciserest training Heart rate based calorie computation.