Need Help with Grommet

[dmjlambert]

I had a heck of a time figuring out the grommet, and parts store guys and even speed shops were useless. The best they could do is suggest I buy a breather from the chrome-gets-you-home section of their store and throw away the breather and keep the grommet that comes in the package. I don't know why the outside diameter is even given as a dimension for these grommets, nobody on Earth would care about that. We need the inside-the-groove or fits-hole-size diameter.