The left side in the direction of travel. It's the right fin when flipped over and viewed from the back. Everyone has likely experienced their own surfboard, or even the nose of another person's board, flying into their face during a wipeout or paddling, cutting their foot with a fin, or damaging other surfers or boards. Hawaiian local DAVID, who surfs on coral reefs, established Surfco Hawaii 25 years ago based on his experiences witnessing various serious injuries, with safety as its concept. Power Flex Fins 4.25" FCS [75A] The core itself has flex, generating propulsion with a spring-like return force during turns. COLOR: CLEAR SIZE: 4.5 inch FIN SYSTEMS: FCS