Includes 2 grooved rulers in a 2:1 Ratio. The 2:1 ratio is the industry standard for quilt patterns. Each ruler measures 4.5″ x 8.5″ and trims 14+ sizes of either single direction or mirror image divided rectangle units. There is a groove to lock the ruler into place on your seam which makes the tough job of squaring up easy and fast. Easy to read numbers and grid lines in 0.5 inches increments.