Trout Knotless Tapered Leaders. Each RIO Powerflex knotless tapered leader is designed for superb abrasion-resistance as well as high knot and tensile strength. The long butt design provides smooth turnover while the supple tippet gives the fly life-like presentation. The graduated tapers have corresponding stepped butt diameters. Tapers are made with thick butts to turn over heavy flies and thinner butts for smaller flies. RIO knotless leaders have a high tech "best maximum pull" ratio to orient the molecules in a linear chain. This means that RIO's leaders return to their original taper after a fight. The light gray color is the most neutral and integrates visually with any background for the perfect camouflage.