Feature:

Heart rate monitor: 1S with optical heart rate sensor, shows you heart rate with PPG, you can see the results more intuitively. 
30 days standby time: Top-level Bluetooth chip and military gravity sensor ensure 30 days ultra-long standby time for a full charging. 
Call reminder: Mi Band 1S will tell you when a call comes, you never need to worry about missing any important calls. 
Sports tracking: Track your sports, record steps, distance and calories, help you achieve your sports target. 
Sleep monitoring: Let you know your deep sleep and shallow sleep, also APP will give you periodical evaluation, help you develop good living habits. 
Silent alarm: Wake you up every morning, will not be late for work; Remind you with vibration, never worry about missing anything. 
Free password to unlock the phone: Forget complex unlock password and gesture, simply raise your hand to close to phones, immediate and safe unlocking. 
Device Requirements: Android 4.4 and above, and supports Bluetooth 4.0 Android smartphones; 
Battery Thickness: 8mm 
Battery Capacity: 45mAh 
Batteries Type: Lithium Polymer 
Input Current: 25mA (TYP) 
Input voltage: DC 5.0V 
Bluetooth Version: 4.0 Waterproof grade: IP67 
Wristband Material: Dow Corning TPSiV
Heart rate sensor: Optical heart rate sensor 
Sensor: ADI military gravity sensor 

Fit models:

Millet 2 / 2S / 2A, millet 3, 4 millet, millet Note, millet 4C, red rice 1S,red rice 2 / 2A, red rice Note, red rice Note2.Adapter Apple iOS 7.0 or later and iPhone 4s / 5 / 5c / 5s / 6/6 Plus / 6s /6s Plus. 
Bracelet unlock Supported models: 
Millet 2 / 2S / 2A, millet 3, 4 millet, millet Note, millet 4C, red rice 1S,red rice 2 / 2A / 3, red rice Note / Note2 / Note3, Bluetooth phone support Android5.0 above 4.0. 

Package Included:

1x XiaoMi 1S bracelet 
1x Charger 
In an original box