Finally, a smarter solution for yard chores. The Sharperblade trimmer blade will replace the frustration from tradition string trimmers. The Sharperblade from Sun Joe is a blade made from nylon embedded in polymer and cut like a mower blade. Its self sharpening system gives you precision when you need it. As you use the blade, it wears down to expose a fresh and sharper new edge. Installs on most trimmers that have a removable head and threaded shaft (most do). Safe on brick, concrete and stone. Blade flexibility maximizes operator safety.