You plug this into your bicycle dynamo and out comes electricity to charge your shit with if you're going at least 12kph ~7,5mph.
Very cool for people who do multi day bike tours and having tested one personally: Yeah, rules!
You might have to do some finnicking with a powerbank that doesn't require you to replug it after it stops charging - I mean you're gonna go below 12kph eventually - but hey, you get some volts out of it to keep your phone or whatever other tech going if you're on a multi day ride with sparse outlets
Here's some data if you're into that sort of thing
my eternal average touring is at like 18kph and I'm by no means a fast boy