Toothpaste in the U.S. is sold by weight, not volume. Unfortunately, the name of the standard weight unit (the ounce) is the same as the name of the volume unit that TSA agents use as a size criterion. Since toothpaste is rather dense, a 4.8 ounce (by weight) tube of toothpaste contains less than the allowable 3.4 ounces (by volume). Does anyone have any experience with TSA agents in this regard? Do they know this, and let that size tube through? Do they see "4.8 oz." on the label and say "No way?" Can they be convinced?