I wanted the smallest possible "vent" for poly fill, so you can refill the cart without having to remove the poly. It's a coffee straw, but I'm using only 1/4 of the circumference. Laid up against the curved side of a 510 cart, it makes a nice small vent that is nowhere near touching the bridge when inserted. I don't want any credit for this, I'm sure this has been done before. Here is a pic:
