Sharpen Your Rotary Blade with Every Cut. This see-through ruler has a diamond carbide edge that will maintain the sharpness of your rotary cutter blade as it spins. The ruler is packed with great features: it is full see-through with a non-skid frosting that keeps the ruler from sliding and makes it light enough to see your fabric through it. A unique red grid system highlights the 1/2" marking. Use both lines to square up blocks or to cut squares effortlessly. There are diagonal dots for fabric positioning and large numbers that are easily visible against any fabric. Has 1/8", 1/4", 1/2" and 1" marks. 6-1/2" x 12-1/2" Ruler.