• GPS model to receive calls and messages from your wrist. • Large Retina OLED display. • Processor up to 2 times faster than series 3. • Daily activity tracking and trends in the Fitness app. • Measures workouts like running, walking, cycling, yoga, swimming, and dancing. • Swim-proof design. • High and low heart rate notifications. • Syncs music, podcasts, and audiobooks. • Secure payments with Apple Pay. • Built-in compass and real-time elevation readings. • Refurbished product, inspected and tested to work like new.