From the Publisher:Chessex mats are made from expanded vinyl to bring you the highest quality mat currently available.These mats, first made available in 2002, build on our reputation for single-sided vinyl game mats. The specially-made vinyl features the same eye-pleasing oyster color as our existing single-sided mats while being made in such a way to give a flat surface for writing. Using water-soluble overhead-projection pens (NOT dry erase, grease pencil, or permanent markers), you can write on the vinyl and remove later with water when the drawing is no longer needed. - BoardGameGeek