If you missed an announcement in the final days of an insane 2020 from the Tax and Trade Bureau (TTB) regarding new rules around allowed bottle sizes, well, you’re probably not alone. The implications of the new allowed bottle sizes—in particular, the 700ml—will be noticed by most everyone pretty soon.

The TTB, more formally known as the Alcohol Tobacco Tax and Trade Bureau, sets the sizes for spirits bottles that get sold in the US. After repealing the Volstead Act and reversing prohibition, Uncle Sam needed a way to effectively and efficiently tax booze—uniform bottle sizes did the trick.

During the half-assed attempt at converting the US to metric in the 70s, the current lineup of allowed bottle sizes was created, named after imperial units such as gallons, but labeled in milliliters. The US fifth, or fifth-gallon, was set at 750ml, just slightly larger than the conventional and then standardized 700ml size used in Europe.