ECG is not intended for use by people under 22 years old. The ECG app is available on Apple Watch Series 4 and later (not including Apple Watch SE) with the latest version of iOS and watchOS.Blood Oxygen app measurements are not intended for medical use, including self-diagnosis or consultation with a doctor, and are only designed for general fitness and wellness purposes.Series 7 is also rated IP6x dust resistant. However, they should not be used for scuba diving, waterskiing, or other activities involving high-velocity water or submersion below shallow depth. This means that they may be used for shallow-water activities like swimming in a pool or ocean.