Adjustable windsurf lines are made from high-density polyurethane.
With the line knotted at one end, you can trim the tubing to any length and adjust with the knot.
The non-corrosive adjustable buckles are attached to nonslip pads to prevent them from slipping on your boom. The adjustments are made using a pre-stretched FSE robline rope. allowing for up to 5"(13cm) of adjustment.