Mille cafe is a Denmark coffee filter made of polypropylene.
Supposedly you can use it for 1000 times, so it is supposed to be good for the environment.
Before using, you need to "season" it by pouring hot water onto it for at least a minute.
Then after brewing the coffee, you pour more hot water down the filter to wash out the coffee grains.
I also washed it with a little detergent after using it the first time because the coffee tasted a little "plastic-y".
I wonder if it will really last about 1000 times?!
UPDATE: 4/2014--it doesn't filter cold-brewed coffee
1/2015: it is quite a p.i.t.a. to clean, very messy as you need to pour hot water over the filter to "drain" the coffee grains into a container (garbage bin)....