Terrain Blocks measure 16" across flat-to-flat (excluding tabs).
Intersection has a cutout for creating a bomb crater. Simply dig out as much foam as you like to create the crater you want. On our sample model we created a lip around the crater using our GCM Scenics Terra-Form product.
The Terrain Blocks are 3mm MDF that is pre-bonded to 1" XPS foam to keep them lightweight and help insure the MDF does not bow and refuse to lay flat on your table. The Terrain Blocks come with small connector "dogbones" that keep the Terrain Blocks from sliding around and separating from each other.