From the front of the book: Ptolus e-Adventure Tiles: Sewers lets you customize miniatures scale encounter areas in the waterways beneath the streets of Ptolus. This set of 25 six inch square tiles provides both main and medium sewer lines as described in Chaper 21 of Ptolus: City by the Spire – complete with walkways, murky water, intersections, and arched stone bridges. In additions, there are ten bonus tiles to link this set with any other e-Adventure Tiles Cave or Sewer set to create ratman tunnels or connections to the deeper sewers below Oldtown. Use the thumbnail tiles in the Introduction file to design your sewer encounters, print only the tiles you need, trim them out, and they are ready for the tabletop. The only thing missing will be the smell.