More than just tracking devices withswimming skills â these thin profiledcenter fins and asymmetrical cuppedouter fins â track harder, cleaner, andinitiate turns with a timeless surf feel. Size 3.0" R Fiberglass Epoxy Construction: Provides a stiff & responsive feel for enhanced performance. Compatibility: Designed exclusively for Ronix boards equipped with the Fin-S 2.0 mounting system. | Ronix Fin-S Floating Blueprint Fin - 3.0" Right