Worn on the upper arm, this lightweight and breathable smart sleep band is available in two sizes for comfort throughout the night Can provide sleep-tracking metrics, including sleep score, sleep stages, HRV and duration of rest (data presented is intended to be a close estimation of metrics tracked) Up to 7 nights of battery life For more insight into your health, the breathing variations feature uses Pulse Ox to check your level of variations while sleeping (this is not a medical device and not intended for diagnosing or monitoring medical conditions; Pulse Ox is required and not available in all countries) Using skin temperature, advanced women’s health tracking provides more insight into your menstrual cycle, including better period predictions and past ovulation estimates (this feature is not intended to support conception, contraception or birth control and is not a medical device) If you don’t own a Garmin smartwatch, Index Sleep Monitor sleep metrics can sync directly to the Garmin Connect app ; if you wear a compatible Garmin smartwatch during the day, your data will seamlessly sync via the Garmin Connect app for more insight into your health and fitness Smart wake alarm gently vibrates to wake you at the optimal time