Publisher's blurb: The Tunnel Wye group of Naked Geomorphs contains 13 tiles, each with three connected tunnel entrances (T), and rock (R) at the remaining three positions. There are actually ten different interconnection patterns; this group contains two tiles for each pattern where all three tunnel positions are adjacent, because those are so useful as edge and corner tiles. Sets A and B are completely interchangeable. I.e., tile T137A can be replaced with tile T137B, without changing the basic structure of your map. Set A has narrower tunnels than set B, with lots of one-hex-wide passages and a few small to medium galleries.