Bass Polska Trimmer Head 8658-GLO Fits Model 63cc Brushcutter (8656) A trimmer head is the most popular type of brushcutter head. It is made of a metal disc with plastic trimmer lines wound around it. The lines slide out of the disc using a special mechanism that makes changing them easy. Trimmer heads are designed for cutting grass, weeds, and small shrubs. An auto-feed trimmer head is a type of trimmer head that automatically feeds the trimmer line when you press the handle. This eliminates the need to replace trimmer lines yourself, which is very convenient. A center-feed trimmer head is a type of trimmer head that places the trimmer line in the center channel of the disc. This feeds the line evenly from both sides of the disc, ensuring an even cut.