Xiaomi Mi Band 2, Ollivan Wristband Bracelet With OLED Display Smart Heart Rate Monitor Fitness Tracker Watch Bluetooth 4.0 Pedometer IP67 Waterproof CACULATE STEPS-- Pedometer Bracelet, good companion for your run or walk, caculate how many steps you have took and how much excersize you made. IP67 WATERPROOF --Fitness Tracker Watch can ensure to work well even geting a little wet in daily life. MONITOR HEART RATE--Heart rate monitors watches help you monitor and analyzes your sleep quality, so as to help you to monitor sleep quality accordingly to have a healthy life SYNC DATAS--Smart Bracelet can sync app datas regularly to analyze your fitness and sleep activities to help you to improve your lifestyle FREQUENT ISSUES-Relax if the mi band stops monitoring heart rate suddenly, please go to Profile-Settings-About, then updating it to newest version, quickly fixed. 0.42 inch OLED display screen with touchpad Support Heart rate monitor Pedometer, Fitness Tracker, Sleep Tracker, Message Reminder, Call Reminder Water resistant (IP67) 20-day standby power Sleep-cycle smart alarm With a Dialog II 4.0 bluetooth chip, ADI sensor Wrist Strap Length 235mm Adjustable Wrist Strap Length 155mm ~ 210mm Battery capacity:70mAh Standby time:20 days Batteries Type:Lithium polymer Input Current:45 mA (TYP) 65 mA (MAX) The main material:Plastic, aluminum Total length:235 mm Adjustable Length:155-210 mm Material:Thermoplastic elastomers, aluminum Measuring method: photoelectric volume pulse wave plethysmography (PPG) Bluetooth chip: Dialog top Bluetooth chip (Bluetooth 4.0) Sensor: ADI military gravity sensor 1x Mi band 2 1x Type C converter 1x Charging Cable 1x English UserManual Low power consumption OLED display Military-grade ADI sensor Power-efficient ADI accelerometer,optical heart rate sensor Resistant to scratches and fingerprints Anodized 0.05mm ultra-thin button Bluetooth 4.0 for faster,stable connections