The Apple Watch brings notification checks and health information display to a new level of ease. No need to bring your phone out. See everything right on your wrist! The Apple Watch Series 4 lets you measure your blood oxygen level with a revolutionary new sensor and app. Take an ECG from your wrist or see your fitness metrics on the enhanced Always-On Retina display, now 2.5x brighter outdoors when your wrist is down. Set a bedtime routine, track, track your sleep, and reply to calls and messages right from your wrist. It’s the ultimate device for a healthier, more active, more connected life. Get all that and an 18-hour of battery life all in this refurbished Apple Watch.