Pathfinder Flip-Tiles: Darklands Fire Caves Expansion: - Rules of Play says:

There's an entire sprawling world of adventure below your feet! Flip-Tiles: Darklands Fire Caves Expansion is the newest expansion to Flip-Tiles: Darklands Starter Set. With 24 full-color 6 x 6-inch double-sided tiles, each stunningly crafted by cartographer Jason A. Engle, you can navigate twisting tunnels, brave bubbling rivers of magma, or explore the lava tubes twisting below a volcanic mountain range. All perfect for the next time the heroes wander too deeply into the depths! Suitable for experienced GMs and novices alike, this product fits perfectly into any Game Master's arsenal. Wet, dry, and permanent markers erase from the tiles! These double-sided dungeon tiles come in convenient packaging for easy storage. Add some fire to your caverns!