A resistance spool (16) for holding lines (38, 40) in a line trimmer head (10) is disclosed. The spool (16) has a rotatable main body (19) having lines (38, 40) wound thereon. The wound lines (38, 40) have free ends (42, 44) which extend radially from the main body (19). Clamp portions (32, 34, 36), on the main body (19), restrain the free ends (42, 44) of the lines (38, 40). The clamp portions (32, 34, 36) restrain the free ends (42, 44) so that the lines (38, 40) do not unwind from the spool (16) when the main body (19) is not rotating at a sufficient speed and allows the free ends (42, 44) of lines (38, 40) to pay out from the spool (16) when the main body (19) is rotating at a sufficient speed. Preferably, the main body (19) includes a hub (20) and axially disposed flanges (22, 24, 26) extending radially outwardly from the hub (20). The flanges ( 22, 24, 26) cooperate with one another to pinch the line (38, 40) such that the line (38, 40) may not unravel during installation of the spool (16) within a line trimmer head (10).