Stay connected with smart features such as music controls and smart notifications for incoming calls, text messages, calendar reminders and more (when paired with a compatible smartphone) Estimates heart rate with elevate wrist heart rate technology. Display size 0.38 x 0.76 inches (9.6 millimeter x 19.2 millimeter). Small/medium fits wrists with a circumference of 107 177 millimeter Wellness monitoring tools, such as all day stress tracking and a relaxation timer, help you manage stress; Includes advanced sleep monitoring with REM sleep Displays steps, calories, distance, heart rate, intensity minutes and VO2 max Effortlessly change your look with industry standard 20 millimeter quick release accessory bands Battery life: Up to 5 days in smart mode; Up to 2 additional weeks in watch mode (hands tell time only). Display resolution: 64 x 128 pixels