PRODUCT OVERVIEW The most rugged and capable Apple Watch ever, designed for exploration, adventure, and endurance. With a 49mm aerospace-grade titanium case, extra-long battery life, specialized apps that work with the advanced sensors, and a new customizable Action button. See the Dimension section below for band sizing information.  KEY FEATURES WHY APPLE WATCH ULTRA - Rugged and capable, built to meet the demands of endurance athletes, outdoor adventurers, and water sports enthusiasts - with a specialized band for each. Up to 36 hours of battery life, plus all the Apple Watch features that help you stay healthy, safe, and connected. EXTREMELY RUGGED, INCREDIBLY CAPABLE - 49mm corrosion-resistant titanium case. Larger Digital Crown and more accessible buttons. 100m water resistance. Customizable Action button for instant physical control over a variety of functions. BIGGEST, BRIGHTEST DISPLAY YET- A bright Always-On Retina display that’s easy to see, even in direct sunlight. More room for adding complications to customize your watch face. FOR ENDURANCE ATHLETES - Advanced metrics in the Workout app, including Heart Rate Zones and Running Form. Precision dual-frequency GPS for accuracy, distance, route, and pace calculations. Trail Loop band is thin, light, and flexible, designed especially for runners. FOR OUTDOOR ADVENTURERS - Redesigned Compass app delivers all-new views and functionality. Mark your location with Compass Waypoints. Backtrack uses GPS to map where you’ve been so you can retrace your steps. Alpine Loop band is extremely rugged and secure to meet the needs of hikers and climbers. FOR WATER SPORTS ENTHUSIASTS - Made for high-impact water sports and diving. The Oceanic+ app puts a dive computer on your wrist. Ocean Band is light and flexible, with a titanium buckle and adjustable loop for a secure fit even during high-speed water sports. MOST ADVANCED HEALTH AND SAFETY FEATURES - Advanced health sensors give you deep insights into your health. Fall Detection and Crash Detection can automatically connect you with emergency services in the event of a hard fall or a severe car crash. Hold the Action button to activate a siren that can be heard up to 600 feet away.