I was a little confused, as normally my beer gets filled in the cup from the bottom up, but now I get it. Pretty clever from a design standpoint. It seems useful for high-traffic places with beers that people don't really care about, but I wonder how it would perform with a beer that actually has more than a 1/8 inch of head. I would think a little splashing action would be needed to get the right amount of head and, thus, give the beer the right "nose" to it.