A spool for a spinning reel is mountable on a spool shaft. The spool includes a spool body that rotates with respect to the spool shaft. The spool also includes a drag mechanism between the spool body and the spool shaft to apply a braking force against a rotation of the spool body. The spool further includes a radiator in the spool body and in contact with the drag mechanism. The radiator rotates with respect to one of the spool body or the spool shaft. The radiator does not rotate with respect to the other one of the spool body or the spool shaft.