The Worx WA0004.M1 Trimmer Line Replacement Spool is a powerful single-line release for added cutting power. Designed with an oval aerodynamic shape known as Doublehelix DNALINE2. This patented design increases edging life up to 25% compared to normal use conditions. The spool comes pre-wound, and is easily replacable. 0.065" diameter line16' length . Over 100 lbs of tensil strength.