Sudroid Bluetooth Smart Bracelet Smart Watch Sports Sleep Tracking Health Fitness Pedometer (Black) Smart wristband with OLED screen, show the steps, Calorie, Distance, Time, Sleep quality clearly.Make your Exercise more regularly,your life more healthy. Host comes with a standard USB port, special design to charge through connecting PC and mobile driver. The bracelet can record the Steps,Distance,Calories for sport data,but it's not a bluetooth partner,can't sync any call or message with your cellphone. Insert the USB stick of the host device into wrist band, then lock the clasp(as shown in the figure);You can adjust the clasp upon the size of your wrist. Sync sport data with apple and android device:Go to App store or paly store, download this APK: "Zeroner"and install it.