Generally I carry my power bank like my wallet, im the guy whose use social network 24*7, so my mobile wont sufficient to use whole day.
My power bank is Mi POWER BANK.i buyed it 6 months back, its still working with out any problem.
my power bank mah is 20800.
I keep charging it 1 hrs per day. so I can use it for 6hrs.
I can charge it for any mobile.
very good quality BUT little heavy in weight and in silver colour it looks cool and very lowest in price.
when I buyed the price was RS=1999.
No issues and satiesfied by using power bank.