Our Spin-e-fex Snowflake templates are so easy to use. The etched markings are easy to see - Westalee's unique Key Gate System allows you to place the Ruler Foot inside the template and then close the opening. This prevents the template from expanding as you stitch and does not leave you with a flat spot in the stitching where you stitched past the opening. With a set of 2 tools you get 4 keys making it possible to quilt 4 different sizes for each of the Snowflake templates. The measurement is the outer edge of the circumference of the circle the Snowflake fits in. 5.5&; 7.5; 9.5; 11.5; but not limited to these size You can easily vary the size to suit your design.