9mm pipes have filters that are larger than those on other pipes. These filters (that have a 9 millimeter diameter) absorb nicotine, moisture and tar. They have been gaining in popularity among smokers, thanks to their outstanding efficiency. The filter (in the form of a cartridge) must however be changed regularly. We recommend replacing it after 3 uses. On our website, we have selected the best 9mm pipes made in Saint-Claude (Eole, Chacom, Butz-Choquin...).