From the review:
The scoop on Battle Boards
So what sets Battle Boards apart?
They’re made of steel, 1/32? thick, with a dry-erase surface
They come in two sizes, 12? (Standard) and 16? (EX), and two grid patterns: “strategic” and “roleplay”; all cells are labelled
Magnets will stick to them, so you can use magnetized miniatures
Between the steel and the dry-erase coating is a “skin” that can be applied during production, allowing for different patterns and the like
Using velcro, you can stick boards together edge to edge to form a larger surface