Garmin Forerunner 935

Product Details:

Offers advanced running and multisport features in a comfortable watch you can wear all day, and it only weighs 49 grams
Provides elevation changes with a built-in barometer; altimeter and electronic compass help you keep your bearings
Evaluates your training status to indicate if you’re undertraining or overdoing it and offers additional performance monitoring features
Provides advanced dynamics for running, cycling and swimming, including ground contact time balance, stride length and more
Battery life: up to 2 weeks in watch mode, up to 21 hours in GPS mode, up to 44 hours in UltraTrac™ mode (with wrist-based heart rate)