Either they need an 8 in strip and only have say a 6 in ruler. Put the first ruler on fabric edge measuring in 2 inches. Then butt the secon ruler against it to cut by. Or if you have your straight edge of fabric on the right side, measure from there with one ruler. Now place a second ruler against it. Remove the 1st and cut with the second. I would do this if I laid the fabric the wrong direction for my cutting(left/right handed) Or if my longest ruler I want to cut by is not wide enough to measure by.