The Mi Band 1S is a low cost fitness device with very good built quality and finishing. It has metal body at top and plastic body at the bottom. It is light weight, just about 15gm. It is come with the 45mAh inbuilt battery. It is take hardly 2 hours to fully charge.
At fully charged condition you can use it 15 to 20 days easily. To use this band you can download the App called MI Fit. It is available on Android and IOS platform. To connect to the phone It can use the Bluetooth. There is a built in Bluetooth 4.0. It measures the heartbeat, steps and many other things.