Phase 5 Fireball Wakesurf Board The Phase Five Fireball Wakesurfer uses the popular skim style Matrix outline and is constructed with our buoyant surf style foam core. When you are in the surf style mood, install the included 3.7 Surf Twin Fin Set at the fin plugs located on the outside rails. Ready for skim style action? Remove the outside Surf Twin Set and install the provided skim style DT Fin in the center position near the tail. Compared to our other surf style boards, the Fireball has redu