Designed by It's Sew Emma, the Starburst 30 Degree Triangle Ruler can be used to create circles and intricate 12" finished blocks. Simply sew together twelve, 30 degree, triangles to create a circle. Equipped with Creative Grid's exclusive grip, this ruler slides easily on fabric yet stays in place when pressure is applied. Use the included instructions or scan the QR code to view a video demonstration. Made in the USA.