Use the Creative Grids 15 Degree Triangle Ruler to create Fans, Dresden Plates, etc. up to a finished size of 46cm . Sew together 24 of these 15 degree triangles to create a complete circle; 12 to create a half-circle; or 6 to create a quarter-circle. Total ruler length is 23cm - 1.3cm . 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!