Fundamentally redesigned and reengineered. The largest Apple Watch display yet. Built-in electrical heart sensor. New Digital Crown with haptic feedback. Low and high heart rate notifications. Fall detection and Emergency SOS. New Breathe watch faces. Automatic workout detection. New yoga and hiking workouts. Advanced features for runners like cadence and pace alerts. New head-to-head competitions. Activity sharing with friends. Personalized coaching. Monthly challenges and achievement awards. Built-in cellular_ lets you use Walkie-Talkie, make phone calls, and send messages. Stream Apple Music_ and Apple Podcasts. And use Siri in all-new ways - even while you're away from your phone. With Apple Watch Series 4, you can do it all with just your watch.