Fitbit Sense is the advanced health smartwatch that helps you tune in to your body with tools for stress management, heart health, SpO2, skin temperature & more. Battery & Power: Battery life up to 6+ days. Battery life and charge cycles vary with use, settings, and other factors; actual results will vary. Use of the always-on display and SpO2 features will require more frequent charging. We recommend charging every few days to ensure you’re always tracking. Water-Resistance: Water resistant to 50 meters. After getting the band wet, we recommend drying the band because, as with any wearable device, it's best for your skin if the band is clean and dry. Heart Rate: Like all heart rate tracking technologies, accuracy is affected by physiology, location of device and different movements. Syncing: The Fitbit app is compatible with most popular phones and tablets. To set up and use your Fitbit products and services, you must install the Fitbit app on a compatible device running one of the following operating systems: Apple iOS 12.2 or higher. Android OS 7.0 or higher.