Hi friends I share my experience about mi 2 power bank which is 20000 mah power bank of mi company. I haved charge my Power bank fully after that I have use in htc 820 dual sim phone. And it charge 6 time my phone from 0-100% battery. Company is telling that u can charge 7 time but it laking behind of that. But is still a great thing. Beacuse I use my friend power bank aslo which is intex 20000 mah power bank but he charge only 5.5 time my phone. For me mi power bank is great choice for u it cheapest and powerful battery is there.contains of box : - usb, power bank , and user manualSpecification : - 20000 mah battery , li - polymer batteries, quick charge 3.0 , two usb port.