5 meters Windsurf line 4mm for extensions and booms

The 4 mm trimming line is a basic component of any windsurfing setup. It is used to adjust sail tension in mast extensions and boom trimming systems. The 4 mm diameter delivers a good compromise between strength and smooth performance in pulleys and rollers. It runs freely without jamming and enables precise sail tensioning during setup and later adjustments. The 5 m version offers extra length and works well with more complex pulley systems, longer mast extensions, or if you want one versatile trimming line for multiple setups.