The Imose Kampe is a dual-SIM, feature phone with a 10,000 mAh battery. With a battery that huge, it also doubles as a power bank. But what really makes it even more ingenious is the fact that yoiu can just pull out the battery and use it as a standalone powerbank without phone functionality. The battery itself has a USB port for connecting to and charging other devices, as well as a micro-USb port for charging it.
The advantage is that carrying the battery is more convenient than carrying the full phone. It is more compact and there is no network drain on it. Here is the full battery:
Here is the micro-USB paort for charging the battery:
And here is the USB port for charging other devices:
Good product thinking, if you ask me. Give the user the freedom to choose how to use the device: as a backup phone and power bank or as a standalone power bank.