I’ve noticed this rechargeable Varta thingy on Thomann, and was wondering if it could be used as a pedalboard supply? The implication seems to be that yes, it could, as the specs show the USB outputs rated as "5V / 3A, 9V / 2A, 12V 1.5A". Which is jolly good, but I can't see for the life of me how the desired output voltage is selected. Anybody got any ideas?
https://www.thomann.de/gb/varta_wireless_power_bank_10000.htm