Husqvarna 539117543  CLAMSHELL VENT

The purpose of Trimmer Line, as opposed to a hardened blade, is to serve as a less durable cutting tool for string trimmers to cut grass without risking substantial damage to nearby trees, fencing, or other surfaces. As trimmer line is designed to wear down during use, it is common to have to replace trimmer line frequently, often by releasing more from the spool within the trimmer head with a gentle bump. Trimmer line can be sold as a spool, preloaded into a trimmer head, or as pre-cut lines for insertion.