precision marking is critical in some situations. With these drawing wheels, you can mark with your Garden Lines rulers directly on a quilt with a fine tip Mark-B-Gone wash out pen and exactly mimic the sewn line. Also, these wheels are critical when marking paper patterns for elaborate planning! Sized for a ultra fine tip sharpie or mechanical pencil, the wheels will allow you to draw the final stitching line, so when you are ready to sew, your rulers will align for perfect sewing. Measuring 1/2″ wide x 1/8″ thick, the center 2mm hole mimics the needle and hopping foot exactly. Made in a vivid translucent purple to make them harder to loose!