I have a Vauen Shanghai sitter, which at its price point, is one of my favorite pipes. Almost all Vauens come with the 9mm Dr. Perl Jr. filter standard and need the
Vauen Tabak (full disclosure, I work for the company in the link) if you want to smoke them unfiltered. The exception is the Auenlands. You can just take the filter out and throw it away.
As a side note, if I'm using a filter in my Vauen, I prefer the Castleford filters.