Cap for water / diesel filler neck

A cap for a diesel filler neck that was used in my fathers camper to put the electric cable to the outside. Designed with a bigger gap to put some foam or a seal in it to achieve a tighter fit.

CAUTION: This is not intended for use on a actual water or diesel tank. Probably it won't seal up perfectly so if you do, it's on your own risk. On tp of this I don't know how diesel and the printed plastic interact, so I highly recommend to not use it on a Diesel tank!

Example filler neck: https://