The Allen A5266 Mainsheet Jammer is designed to prevent the sheet from wrapping round the block resulting in extra control for faster, smoother tacks and gybes.

By moving the block outward from the swivel and angling it away from the cleat the mainsheet system creates turning force on the block and jammer meaning the cleat will always be forced to point away from the boom and towards the helm.

Normal length arm with cleat, ratchet block not included