3.38140 Ounces or 3 Ounces? from I Demand the Right to Pack Chianti in My Carry-On Slideshow

I Demand the Right to Pack Chianti in My Carry-On Slideshow

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3.38140 Ounces or 3 Ounces?

Why are travelers at most of the world’s airports today permitted to pack vessels containing up to 3.38140 ounces (i.e., 100 milliliters) of liquid in their hand luggage, while travelers in America are limited to 3 ounces? Or are they?