FCS 12&rsquo;6&rsquo;&rsquo;- 14&rsquo; Adjustable SUP Race Comp Calf Leash As with all FCS surfing leashes, an engineered polyurethane cord provides the ultimate combination of strength, stretch, and elasticity. The adjustable rail saver adjust from a length of 1.8' to 3.3', so it will work with almost any size racing or other paddle board.