We Machine Our Power-Drive Aluminum Transmission Pulleys from aircraft-grade aluminum. They are a very strong yet lightweight pulley. Reduce “Rotating Mass” and get a quicker throttle response and more fun ride. We coat them with Mil-Spec. hard-anodize to get superior wear resistance. You will get major weight savings over an equivalent sized steel pulley. So if you are into acceleration this is the pulley for you. Different sizes are available to tweak your gearing needs. Please check if your belt will accommodate the gearing change before ordering.