UNIFIBER HD SDM ALUMINIUM MAST EXTENSION (U-PIN)When your sail requires solid downhaul tension, HD SDM extension is the right tool for the job. The base itself is made out of high quality polyamide to withstand the high tension downhauling. Featuring a 3 roll pulley, the extension decreases the effort required from the user to downhaul even a slalom sail. The functional length can be adjusted with one hand using the open and slide collar. FEATURES Reinforced base is compatible with all racing sails