Pack Of 10 These spools are a great way to keep your threads and ribbons. Just flip up one of the sides, wrap your thread, flip down the side, and you have enough tension on the thread to keep it taught, but just a small tug releases it as you need it. They are ideal for storing ribbons as they keep the ribbons neatly wound. Large spools have a diameter of 6cm. Small spools have a diameter of 4.5cm.