This texture can temporarily replace one of your seamless textures for applying, mapping materials such as wood, concrete, etc. . It roughly shows the user roughly the scale and orientation that their finished materials will have–just by looking at it. When you are done, the original material may be swapped back.
The 2048x2048 texture can be either resized, or cropped to suit your needs.
I used a version of this to map seamless metal materials on this. This one did not have the bias arrows on it: