See your current/continuous heart rate and train using customizeable heart rate zones without the need of a chest strap 6 customizable interval timers with looping feature and 5 customizable alarms. Track the calories you are burning during your workouts Save up to 30 files with 50 laps of run data then recharge your battery for your next workout Rechargeable battery, and water resistant to (30 M): withstands rain and splashes of water, but not showering, swimming or submersion in water. Heart rate monitor; optical sensor; harm zones; calories burned; integrated USB; 6 interval timers 1/100 sec chronograph; 30 run x 100 lap data storage; 5 alarms; rechargeable battery; el backlight; 30m water resistant Quartz movement Case Diameter: 41mm Water resistant to 99 feet