This ruler includes easy to read black and white markings allow you to cut half-square triangles up to a finished size of eight inches. The tip of the ruler is trimmed allowing multiple triangles to be cut from the same strip of fabric. Ruler includes 0.25" seam allowance. This ruler also easily slides over fabric until pressure is applied then the exclusive gripper on the backside of the ruler hold the fabric in place while you cut, to eliminate slipping and miscuts.