Rio Fly Fishing Power Flex-Knotless 12' 4X-Fishing Leaders, Clear RIOs Powerflex Trout leaders feature a powerful butt section that provides unsurpassed turn over for effective wind penetration and to easily cast streamers and indicator rigs. Each leader is made with an advanced copolymer material and is designed to help you cast better and fish more effectively. Perfection loop in the butt for easy rigging