A sheath for a fill-rite nozzle that increases the diameter from 20mm to 24mm. This is intended for use when fueling a US diesel automobile which needs a 15/16" nozzle to open the fuel inlet restrictor.
I printed mine using TPU. Good layer adhesion is critical. You would not want a section to break off & fall in the tank.
USE AT YOUR OWN RISK
The author hasn't provided the model origin yet.