Stokes Filter Replacement filters come in a set of three. After 300+ uses, simply replace the air filter. Simply exhale your smoke into your FLTR, and odorless air will emerge out the other end. It is ideal for minimizing odors caused by smoke. The Stokes filter replacement cartridge is simple to replace and ideal for anyone who wishes to use the Stokes Filter Design. This product has features such as stokes filter cartridges, a filter capacity of 300-500 total uses, eco-friendly cartridges, and three cartridges included. Get Stokes Filter Smoke Odor Eliminators with Replaceable Filters 3 Pack at Amazon Store for the lowest price.