The ECG app is available with the latest versions of iOS and watchOS on Apple Watch Series 4 or later. See apple.com/watch for compatibility details. The ECG app is not intended for use by people under 22 years old.Compared with Apple Watch Series 3.ISO standard 22810:2010. Appropriate for shallow-water activities like swimming. Submersion below shallow depth and high-velocity water activities not recommended.To use Emergency SOS, your iPhone needs to be nearby. If your iPhone isn't nearby, your Apple Watch needs to be connected to a known Wi-Fi network and you must set up Wi-Fi Calling.GPSAlways-On Retina display30% larger screen2Swimproof3ECG app1Electrical and optical heart sensorsBuilt-in compassElevationEmergency SOS4Fall detectionS5 SiP with up to 2x faster 64-bit dual-core processor2watchOS 6 with Activity trends, cycle tracking, hearing health innovations, and the App Store on your wristAluminum caseProduct Accessories Includes:Watch Series 5 Smart WatchSport Band (can be configured for either S/M or M/L length)1m Magnetic Charging Cable5W USB Power Adapter