Use this to sew together twenty-four separate 15 degree triangle units to make a full circle, twelve for a half circle and six for a quarter circle. Make Fans, Dresden Plates and more with a finished size of 18″. Vertical line can be used to fussy cut stripes or cut half triangles. Angled lines can be used to create intricate blocks. Ruler includes .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 miss-cuts.