I maintain one filter cob for when I want to dampen down a full-strength blend, which is rarely. I use adaptors in filter pipes to make them non-filter, since for me, smoking without an adaptor gets too much air in the mix and diminished the flavor, a matter of personal choice. I'm intrigued that this thread was revived after years. I think filters, all the various varieties and interchangeable use of some (especially 6 mm filters and adaptors) is confusing to new pipe smokers, kind of a drag on their picking up the hobby, but essential to learn. A number of my Sav's were bought as non-filter pipes, and I have adaptors in the others. Other pipes I avoid just to avoid their different filtering systems -- Brigham, Carey, 9 mm, etc.