I like how the dude has 3 hands...

It's for specifying containers in the same or a different docker-compose:

https://github.com/qdm12/gluetun-wiki/blob/main/setup/connect-a-container-to-gluetun.md

I inherited my name from the previous Dread Pirate Roberts...

The 'bit' of polycarbonate derived from oil and aluminium mined from earths resources?

I dunno, kinda feels like a win for the environment.