Game Tiles Dungeon Passage Pack 1/Flat Edge is made of "Dwarvenite" and expands the Games Tiles Base Set. It was offered as an add-on pack during the Cavern Kickstarter. The pack comes in both painted and unpainted versions.
The Game Tiles Dungeon Passage Pack 1/Flat Edge comes complete with these 10 pieces:
(10) Passage, Dungeon, Full