Paraphrased from publisher's blurb: 24 double-sided 6"×6" map tiles that can be used to navigate twisting byways of sludge and sewage. Combined with the urban starter set, allows you to quickly create sprawling sewer complexes. Includes: pools of sewage narrow byways slimy intersections ladders to the street surface-side grates filthy whirlpools Also compatible with the sewer system map pack, and flip-mats: bigger sewer, thieves' guild, and seedy tavern.