Helix design copolymer nylon resin and synthetic trimmer/edger line Pliable and flexible allowing for the line to stretch and cushion on impact with hard surfaces Aerodynamic shape allows less drag for more efficient cuts 100-pound of tensil strength compared to old lines that only offer 68-pound of strength Spools fit worx series trimmers/edgers: wg150s,151s,152,155s,165,166
