From Paizo's site:
Flip Mat: Darklands features a maze of interconnected underworld tunnels. The Flip side features a huge, cavernous chamber.
Flip Mat: Darklands measures 24" x 30" unfolded and 8" x 10" folded.
GameMastery Flip-Mats are designed to make your game portable and affordable. They're made with durable, laminated card stock and can handle dry erase, wet erase, and even permanent marker!
Usable by experienced GMs and novices alike, this product fits perfectly into any Game Master's arsenal!