This 20-1/2 inch square 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. The ruler slides easily over the fabric until pressure is applied. Then, our exclusive gripper holds the fabric in place while cutting, eliminating slipping and miss-cuts!