Get a battery boost from the sunlight, so you can go longer between charges;;Special Feature:Backcountry Ski; XC Ski Dynamics; MTB Dynamics; Surf-Ready Features; Animated Workouts; Wrist-Based Heart Rate; Body Battery Energy Monitor; Advanced Sleep Monitoring; Respiration Tracking,Hydration Tracking; Performance Metrics; PacePro Technology; Recovery Time; Daily Workout Suggestions; Power Manager; Solar-Charged Battery; Pulse Ox Sensor; ABC Sensors;Water Resistant: Yes Need running pace guidance that knows the terrain? Check out the PacePro feature Upgraded activity profiles now let you track more, such as specialized Grit and Flow measurements while mountain biking Multisport GPS watch with solar charging capabilities uses a Power Glass solar charging lens and custom power manager modes to achieve long-lasting battery life