Built in GPS built in to acquire satellites quickly to track how far, how fast and where you run, even under tree cover. No phone required24/7 heart rate monitoring warm gives you heart rate all day and night no additional Strap required. Display resolution 128 x 128 pixels. Lens material : Chemically strengthened glassVibration alerts helpful vibration alerts notify you of running prompts, activity tracking milestones, smart notifications and virtual pacing progressUpdated display perfect for indoor/outdoor viewing, smart connectivity auto uploads, smart notifications, live track, music controls and automatic software updatesDisplay size 0.93 x 0.93 inch (23.5 x 23.4 mm), sunlight visible, transflective memory in pixel (MIP), water rating 5 ATM, Smartwatch Mode up to 9 days, GPS mode up to 13 hours