This is a mug, but with a twist! It works on the same principal as the pythagoras cup (http://en.wikipedia.org/wiki/Pythagorean_cup), siphon of the original cup has been moved to the handle of the mug. The mug takes a fair amount of time to drain due to the small size of the spigot, and it does not drain all the way due to the small pressure gradient at low water levels. Warning, do not use with hot liquid. I am not responsible for anything that happens due to the use of this cup.