From the publisher's Website:
Illustrated cardstock terrain tiles for use with the Dungeons & Dragons Roleplaying Game.
This roleplaying game accessory gives Dungeon Masters an easy and inexpensive way to include great-looking terrain in their games. This set provides ready-to-use, configurable tiles with which to build exciting encounter locations. This particular set emphasizes swamp terrain and serves as an extension to the Dungeon Tiles Master Set: The Wilderness boxed set.
This accessory contains six double-sided sheets of illustrated, die-cut terrain tiles printed on heavy cardstock.