Basically it's just a big glass bulb atop a carafe. After you pour the boiling water through the filter into the carafe, you put the bulb on, and the water vapour condenses on the glass. There is a plastic stalactite attached to the inside of the bulb, and it hangs directly overtop the filter so that condensed vapor will drip back through, landing in the pot once again. This stalactite has a wide base to increase collection surface area.
If you're going to continually heat your coffee, you might as well use some of that energy to extract every last bit of flavour out of your beans.-- Cuit_au_Four, Dec 10 2006 You don't want to over-extract your coffee. Extract for too long and you extract bitter, unpleasant flavours.-- webfishrune, Dec 11 2006 Is there a kosher version?-- angel, Dec 11 2006 Only for men, [angel].-- m_Al_com, Dec 13 2006 random, halfbakery