UNUSUAL DATA MARKING: If the SpO2 level is lower than the preset threshold and heart rate is lower or higher than the preset threshold, the device will mark it in the report.UNLIMITED STORAGE IN APP: When the device is connected to the APP via Bluetooth, the data will be uploaded automatically. The built-in memory can store 4 groups of 10 hours of data on device.RECHARGEABLE: The device runs automatically when you wear it, up to 16 hours for a full charge.NOTE: It's not a medical device. This device is for Sports and Aviation use only and not intended for medical use.It is suitable for customers with a finger perimeter of 2-3.2 inch, roughly the size of an adult's finger.