If you want to use the small, 12V astronomical mechanics with some kind of powerbank, the USB-DC converter 5V-12V inverter cable is the solution, as these cables also include a built-in 5V-12V converter. The converter can deliver about 800 mA at 12V. It is not guaranteed to work with all types of powerbanks, but is expected to work with those that can also deliver 12V.
The cable length is approximately 1 m.
Recommended for use with smaller azimuth SkyWatcher mechanics (Virtuoso, AzGti, Az-Goto, etc.)