The Chinese Amazon-Seller Aukey is now widely used here; Here is the 20,000mAh Powerbank with Quickcharge 3.0 as usual on Amazon. The price seems steep for a Powerbank, but there are also all sorts of extras that go beyond the pure capacity.
In addition to the high capacity of 20,000mAh, which with the usual smartphone batteries with about 3,000mAh for more than 6 charges, is enough, especially the present Quick-Charge 3.0 standard, with which you not only often, but also damn your devices Can be loaded quickly – provided the device supports the standard as well. This is particularly true of high-end devices such as the Galaxy S7 but also the Xiaomi Mi 5.
In addition to two separate USB ports for simultaneous charging of two devices, the Powerbank has a micro-USB and a lightning port , which can be used by users of iPhones as well as by owners of other devices.