The Handi Quilter Mini Scallop Ruler has a straight side and a scalloped side. Use the straight side for stitch-in-the-ditch. Use the scalloped side for perfect mini-clamshells. The package has instructions for use, safety tips and design ideas. The ruler is 20cm long and 7.6cm wide. It is a quarter of an inch thick. Handi Quilter rulers work with all mid-arm and long-arm quilting machines, regardless of manufacturer. High quality acrylic is used for its strength, clarity and durability. The quarter-inch thickness of the template provides safety when a hopping foot is used. Markings are etched, not printed, for long-lasting accuracy.