Publisher's blurb: The Tunnel Passage and Deadend group of Naked Geomorphs contains 30 tiles, each with a pair of connected tunnel entrances (T), another deadend tunnel entrance (T), and rock (R) at the three remaining positions. Sets A and B are completely interchangeable. I.e., tile T89 can be replaced with tile T89A ithout changing the basic structure of your map. Set A has broader tunnels than set B, with no one-hex-wide constrictions.