This is the same halyard FLAT Rigs incorporates in all of our professional grade complete rigging kits. You get two 500 lb. 50′ bails of military grade parachute Dacron line- guaranteed not to stretch (because it is cotton-free). Unlike mono, this braided Dacron provides great grip when wet and works seamlessly through our Ronstan block pulleys used in our cords. When used with our Professional Grade Shock Cords, your outrigger lines are guaranteed to remain as tight as the day you rigged them- for years to come.