I am using mi power bank 2i 10000mah for my vivo smartphone device which I brought it from online market.
This is very good and powerful power banks which
I had ever used in my life.I keep it in charging before I go to sleep and I will remove charging at 6am in morning. In day time I and my friends will use it in college to charge our phones.
It is very use full to e and to my friends in our college. It is less in size.And it is very good in it's looking this power bank. This is very less in Weight also. It is easy to carry to all places where ever you wanted to take it or where you wanted to go.
I am very happy with it's performance