Oregon 20-106 Platinum Gatorline 1/2-Pound Donut String Trimmer Line 0.105-Inch Gauge Compatible with most trimmer heads .105" diameter, 1/2 Lb High resistance to abrasion, breakage and welding (up to 498 degrees F) Less noise and engine drag compared to round nylon lines Armored exterior and Flexible core High resistance to abrasion and breakage. Flexible core provides outstanding durability. Less engine drag, vibration, and noise. Engineered to resist welding up to 498 F. Outer layer prevents welding. User friendly donut  fewer tangles. High strength inner core resists breaking. Long-life, excellent strength. Fits all standard trimmer heads. User-friendly donut, limits tangles. Fits all standard trimmer heads. Effective in all cutting conditions.