FCS II JS Modern Keel Performance Glass Twin Surfboard Fins - XL/WhiteThe FCS II JS Modern Keel Performance Glass Twin Fin Set. The JS Modern Keel is an upright keel template designed for the JS Red Baron and other specialty fish shapes. Featuring a wide base and a relatively small sweep (rake), this high area keel provides control through the face and pivot in a tight radius. Upright keel template designed for traditional fish shapes. Lower sweep (rake) than most conventional, wider based keels which allows it to pivot