This is a special mat I had commissioned for a night-battle, Second Bedriacum, and I decided to get four extra ones printed. The mat is a darker version of the plains mat, and acts as a visual cue that it is night time. To make matching terrain for my game, I over-sprayed surplus dark green trees and hills with black paint- it looked very effective and really said "night time". 

The mat has an extremely unobtrusive 20cm white cross grid (just visible to the top left of the unit in the second image) and can equally be used for games that don't require a grid.

If you are looking for a mat for a battle fought in overcast weather, in the evening or at night, this is probably the only design in the world, and there won't be any more once it is gone!