Troy-Bilt 791-153619  Outer Trimmer Spool Assembly, 2

A Trimmer Head on a String Trimmer rotates trimmer line in order to edge a lawn and cut grass in hard to reach places. A trimmer head may feed trimmer line with a bump feed, automatic feed, or fixed line feed. Bump feeds can be damaged by breaking the springs, either by bumping too hard, or continuous use. Automatic feeds may break down in the internal motor, while fixed heads may be the most durable. Trimmer heads are a common replacement on a string trimmer and can be easily replaced.