Today I used my Bent Egg Lorenenzetti (smooth) for the first time. Made in Italy, It has an option to use a .09 mm filter. I bought "White Elephant" charcoal filters with it. Never used charcoal filters before. Not sure how long an individual filter lasts. How many smokes one gets out of one filter. If anyone knows let me know. I smoked some Boswells Northwoods in it and was wondering if the filter would have any effect on the flavor. No change detected. Not sure the real usefulness of using a charcoal filter, but enjoying my new pipe anyway.