Pro Sportfisher Soft Sonic Disc is made from reinforced plastics. These versatile discs are strong, super light and very effective. The term "sonic" in this product does not mean that it emits sound and vibration like Pro's Propeller, rather, this disc is vented and shape optimized to allow casters to get it out of the water and on the way with authority..."sonic" speed if you will! The venting holes allows water to flow through the disc adding life to soft materials, therefore making it an absolute joy to cast and fish. The Pro Softsonic disc is also great to lift/prop wings and hackles, without damaging the delicate fibers. Turn it and you have a wobbler like action. Now that is versatility!