This 20-1/2 inch square, designed by Rachel Cross, features easy-to-read black and white markings printed in 1 inch grids marked in 1/8 inch and 1/4 inch increments. Use the easy-to-read, black numbers (printed on white dots) and the 1/4 inch grip sides to cut whole inches. The 1/4 inch dashed lines printed on two adjoining sides aid in trimming seam allowances. Use the patented Turn-A-Round feature -- designated by the easy to read, numerical white numbers (printed on black dots) and the 1/2 inch grip sides to add the 1/2 inch seam allowance. A 45 degree angle is printed in black and is used to trim half-square triangles to size. White horizontal and vertical lines are printed on the square so the center of the ruler is easily distinguishable. Use these lines to square up blocks based on four-patches or embroidered and appliqued blocks. The ruler slides easily over the fabric until pressure is applied. Then, the Creative Grids exclusive gripper holds the fabric in place while cutting, eliminating slipping and miss-cuts!