This 50cm (20") ruler holds whatever curved shape you put it in. Ideal for making quilted pictures and appliques with curved lines, marking curved lines for beading, sequins, or ribbons, duplicating rounded shapes on patterns, or creating design lines like armholes and necklines. Patterns can be easily altered by adding design lines, or changing a straight line to a curved one. The width of the rule corresponds to the seam allowance.