Key Features . Built-in GPSTrack your steps monitor your heart rate and more!Compatible with Android and iOS SmartphonesWater resistant to 50 metresFitbit Charge 4Take your goals further with this water-resistant health and; fitness tracker packed with built in GPS innovative heart rate features Fitbit Pay and more. Active Zone MinutesFitbit has created a new metric Active Zone Minutes (AZM) to help you work out smarter as a minute of walking and a minute of running don’t provide the same benefits. By using your personalised HR zones to alert and reward you for higher intensity movement Fitbit makes it easy for you to hit your health targets. Smart WakeEnable Fitbit Charge 4’s Smart Wake feature and this handy device will find the best time to wake you up (based on your optimal sleep stage) starting 30 minutes before the alarm time that you set. Don’t worry if this feature isn’t activated – your alarm will go off as per the set time. Sleep StagesFitbit Charge 4 can track your light deep and REM sleep and then provide insights about your slumber. Sleep ScoreThanks to built-in HR monitoring Fitbit Charge 4 can help you better understand your sleep quality each night based on your heart rate time asleep and restlessness. Dive inThe Fitbit Charge 4 is water-resistant to 50 metres. This device can be worn in the pool or shower however please don’t take it into the sauna or soak in the bath with it on..