PLAY X STORE Bluetooth Smart Sports Bracelet Watch,Activity Monitors,Fitness Wristbands.Black. Fitness tracker is applied by professional Bluetooth RF signal and own-developed algorithm,the accuracy can reach 95% and above. Once the activity tracker connected to smartphone, the activity monitors will record and analyze your activities and sleep status automatically. 5 modes HD displayed on the screen of exercise tracker :Time mode,Pedometer mode,Calories mode,Distance mode and Sleep monitoring mode. Keep the fitness trackers screen horizontal and turn over wrist,then it shows time and take picture when the APP program stars. Vibrating alert,when having a call or smartphone beyond 16 FT,never miss important calls also anti lost phone.