9mm pipes give you many options.They are great for new pipe smokers, get rid of gurgling ,or too much moisture which is the main culprit for pipe tongue and burn.tone down harsh blends. Make cheap tobacco passable.Take very little taste away, if any.Give you choices i.e.:Paper , charcoal, meerschaum, paper and charcoal, or an adapter which gives you the non filtered pipe that many feel is the holy grail. Most pipes come in 9mm,But you might have to shop over seas. Many stores here are starting to carry 9mm,BECAUSE,They are becoming popular. People will tell you that filter pipes are cheap pipes. THEY ARE WRONG. Most of the best pipes can be had in 9mm. I like both the 9mm and good quality straight pipes.They both have their place, as do 6mm pipes Also and I know this will start a fur fight,But if you get a good deal on a straight and have a lot of problems,you can have it converted to 9mm and if not possible due to a small shank,You can still filter it with 3mm filters. Yes! There are 3mm filters available.No matter what you decide You Will have to learn proper technique etc. and this is the place to learn and ask. You are among many Great Pipe smokers that will help you along. Good luck. P.D.