JS Sub Xero HYFI 3.0 5'9 Surfboard - FCS II5'9" x 20 3 4" x 2 3 4" 35. 3L The JS Sub Xero Surfboard. To create the JS Sub Xero Surfboard FCS II, JS combined the new Xero with our long running summer favorite, the Psycho Nitro. It has the Nitros ultra fast low to flat rocker and full outline, but with the nose pulled in a touch, and a wider, straighter tail. In the engine room, vee in the nose prompts quick rail to rail transitions, moving into a deeper single to double concave, which helps the