Apple Watch Ultra 4 GPS + Cellular, 49mm Natural Titanium Case with Natural Titanium Milanese Loop - Large Apple Watch Ultra 4 is the ultimate running and sports watch with multi-day battery life to go the distance.² It delivers game-changing health and fitness tracking, enabled by the most accurate heart rate sensing in a wearable.¹ With high-frequency HRV readings for insights on stress, recovery, and your readiness to take on the day. And now every day is more effortless with Siri AI³ and Audio Intelligence.⁴