The Karver KFX1 Halyard swivel is designed for use on structural/permanent wire forestays. Situated below the Head swivel, the halyard swivel is a connector between sail head and halyard and allows the sail to be hoisted or lowered on the permanent forestay using the existing halyard setup. The Karver KF1 Halyard swivel can be used on a forestay of maximum 7mm diameter. This product is for use on a wire forestay only - not suitable for composite stays.