This ruler includes easy to read black and white markings allow you to cut 2-1/2; 4-1/2 or 6-1/2 inch triangles or half triangles. Angled lines can be used to create intricate blocks. 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.