A stencil for airbrushing onto felt sheets to create your own battle mats in 1 inch hex grid. The hexes are roughly 1" center to center in all directions so you can count hexes instead of inches when playing wargames. Also makes deciding facing for rear or side armor when shooting at vehicles flanks easier if you're familiar with how Classic Battletech uses hexes.
Print it, tape some newspaper to the edges to further mask, then airbrush through it onto your felt whatever kind of design you want.
The hex lines are the masked portion so if you use a green felt and airbrush on different shades of green and brown you can have a nice grassy scenic with the original green showing through for the hex outlines or similarly if you do space battles you can airbrush and sprinkle paint for stars and nebula on a black felt and still have the plain black outlines for hex spaces.