From Paizo website:
Even adventurers who feel at home fighting dragons feel uneasy in the swamp, where tiny insects bring terrible disease and one can never be sure just how deep the water might be—or what might lurk beneath it! Flip-Mat: Swamp brings the horrors and dangers of the swamp to your tabletop, the perfect place for putrid encounters sure to put your players on edge.
This portable, affordable map measures 24" x 30" unfolded, and 8" x 10" folded. Its coated surface can handle any dry erase, wet erase, or even permanent marker. Usable by experienced GMs and novices alike, GameMastery Flip-Mats fit perfectly into any Game Master’s arsenal!
On tabletops across the world, the Flip-Mat Revolution is changing the way players run their fantasy roleplaying games! Why take the time to sketch out ugly scenery on a smudgy plastic mat when dynamic encounters and easy clean-up is just a Flip away?