The grid method dates bank to ancient Egyptians and was used by great masters like Leonardo Da Vinci. It can get rather complex but in its basic version and with this tool it allows you to look at a scene in eight sections. This allows you to focus in on each area to do a sketch or after to modify a sketch. This very useful tool is small and easy to hold. If you are not using one we know you will be amazed at how such a simple tool can enhance your work. 3" x 4".