You can power your 4G Router with this small power cable through your mobile power bank. make sure you power bank handle 5V 2A ratings other wise there will be problem working with 4G router.
Please note some fiber optic router are not support to this cable.
Specifications
Current
0.8A ~ 1A
Input Voltage
5V
Output
5.5mm DC Connector
Output Voltage
12V
USB
USB-A Male