Omigrid-Triangle Ruler is made from a durable acrylic plastic and laser cut for a smooth edge which allows for easier, deeper cutting of fabric layers. The patented double line effect is printed in black and yellow which allows the user to see the grid on both dark and light fabrics. Designed for left and right handed users. Right Triangle 9 1/4" Diagonal- for creating quarter-square triangles up to 9" which are used to make up to 9" quarter-squares. 1/4" seam allowance is already calculated in the ruler. 9 1/4" Wide x 4 3/4" High. Priced per triangle.