Worx, Replacement Helix Line Trimmer Spool, Fits Model #WG150, .065" Diameter Line, 16' Length, Grass Trimmer Line 2 Pack For Cordless Series: WG150s,151s,152, 155s, 165,166 GT Cut Case, WORX 2 Pack Timmer/Edger Line Is Made From A Patented Copolymer Nylon Resin & Syntheic Material Designed With An Oval Aerodynamic Shape Known As Doublehelix DNALINE2, This Patented Design Increases Edging Life Up To 25% Compared To Normal Use Conditions, This Patented Resin Line Is Softer Allowing For The Line To Stretch & Cushion On Impact With Hard Surfaces, It Has Over 100 LBS Of Tensil Strength Compared To Old Lines That Only Offer 68 LBS Of Strength, DNA2 Trimmer Line Is Durable & Flexible For Longer Life.