These Gamma processed leaders are IGFA rated. Which means that theses leaders are of special interest to World Record hunters. All leaders are 9.5 feet long. 0X-3X leaders are made with stiff .025 butt diameters for turning over large flies. 4X and 5X leaders have supple .021 butt diameters for soft presentations. 6X leaders have supple .019 butt diameter for even softer presentations.