Stitch inside this ruler to create crisp, sharp points creating right triangles.  Use to stitch parallel concentric triangles or a spiraling triangle design in the setting triangles around the edge of the quilt.  The advantage of this tool over a straight edge is the fact that you only have to do minimal movements of the template to create the design rather than positioning the straight edge 3 times for each round.  Saves wear and tear on your arms and shoulders!