Barrel Clips for Fender Emblems

I see there are barrel clips for attaching emblems to sheet metal via the posts on the emblems. The clips come in sizes to accommodate 1/8" studs and 3/16" studs. My emblems have 1/8" studs and some sort of adhesive or plastic coating that is 3/16" in diameter. Which barrel nuts do I use? Is the plastic there to hold tighter using the 1/8" barrel nuts, or to I count the plastic in the diameter and use the 3/16" barrel nuts.

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