I have been weed cutting for 35 years and have used every size and style of line that is available. This Black diamond line, under the proper conditions, is by far the fastest cutting line that is available. I use around 3000 feet of line per season (April-June) here in the Northern California foothills where the weeds are both tall and tough. Currently, I run two Echo SRM 410U (42.7cc) machines and use several different brands of line for different conditions, but the Black Diamond .105 is my choice for fast work in open areas. In rocky, wooded areas where I use substantially more line, I often switch to other styles of line that are more durable when cutting around rocks, sticks, and debris.
Justin Gnass "Just-Right Weedcutting"