A wound-core golf ball having a polyurethane cover is disclosed. The ribbon is transversely slit to divide each ribbon into at least two individual wing portions. Each of the two flanges is equipped with a notch that opens at the free edge of the corresponding flange, wherein said two notches are disposed facing one another. A fastener inserted into the bore is configured to retain the conductor inserted into the opening, and the arm is configured to deflect to provide a spring force that secures the fastener against the conductor during the heating and cooling cycles.