Oregon 22-405 Magnum Gatorline Square.105", 1 Lb Outer shell Prevents welding Flexible core Break-resistant Fewer tangles Long lasting 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.