A rudder of maneuverability looks like a normal rudder, that would be found on a conventional ship.
When installed on a spelljamming ship, the rudder improves the maneuverability of that ship. It has no effect on a ship that is not flying at tactical speed.
Rudders of maneuvrability are created by elven mages working in the Cenbreȃ shipyards on Cenalterien. Cenaltern is an asteroid close to the centre of the asteroid cluster called Greela in the crystal sphere called Greyspace.
The first rudders of maneuvrability were developed exclusively for use by the Elven Imperial Navy. In more recent times elves, outside the navy, have been able to buy the rudders, but sale to non-elves is forbidden. Severe punishments are handed out to people flouting this embargo and anyone caught doing this may even be put to death.