It’s basically a tube with a filter at one end and a plunger. You fill the tube with ground coffee and hot water then use the plunger and air to force the water through the filter into your cup. Since it essentially makes espresso, you need to dilute the resulting coffee with hot water if you want regular coffee. The result is exceptionally good coffee, better than you’re likely to make yourself without spending a lot more money. It’s also easy to clean since you can pop the used grounds right into the trash. I haven’t had it long enough yet to know the real economics but it should be more than price-competitive with most work cafeterias.

I got mine at Amazon.com but lots of other places sell them too.