This co-polymer resin material was developed exclusively for Orvis and is sold by no one else. Very supple for a lifelike presentation, Super Strong has the highest strength(psi) of any nylon material tested. The nylon molecules are reinforced by a special resin system—stronger than anything else available today—3.5 pounds in 6X and a full 6 pounds in 4X. You can use lighter tippets to fool more fish without worrying about breaking them off. The strength of knotted Super Strong Tippet is higher than any other nylon material and much greater than that of fluorocarbon tippet materials. Line retainers included on each spool.