One set of 6 Worx replacement spools # wa0010. Bin WA0010 The WORX replacement spools for the 18V, 20V 24V cordless trimmer features a single line release and is loaded with our proprietary DNA double helix cutting line for superior cutting performance. Each replacement spool comes pre-wound, and can be replaced easily right on the spot. The DNA trimmer line is superior to standard round line by producing an improved cutting action which helps to keep grass healthier and greener. Its aerodynamic shape also reduces noise and flutter. DNA2 DoubleHelix Line The revolutionary DNA2 DoubleHelix line is superior to the standard round line by producing an improved cutting action, which helps to keep grass healthier and greener. The patented polymer blend is specifically designed to last longer when edging against rough surfaces, and the aerodynamics reduce noise and line flutter.