The Echo 311155066 is a Cross-Fire® .155" 1 lb Donut Trimmer Line. ECHO's best selling professional-grade trimmer line – Cross-Fire®, features a unique in.plus-shape in. design that offers eight cutting edges to deliver optimal cutting surface through the most harsh environments. Dense weeds, brush and hard surfaces are no match for Cross-Fire's strength and durability. Cross-Fire is ideal for professional landscapers and homeowners alike who are looking for an aggressive cut and high-performance durability.