From the Kickstarter description:
Tact-Tiles are highly portable, rigid, thick plastic, wet and dry-erase, gaming tiles. No more erasing the mat and starting over when the PCs run off the edge! And no more fussing with a rolled up mat!
The new run of Tact-Tiles are 100% compatible with the original Tact-Tiles from BC Products.
If you are a gamer who uses miniatures, or just in need of a good portable dry-erase and wet erase solution, Tact-Tiles will provide you with the best solution for a play surface.
This set has six tiles with 1" grid lines.