The ST (Square Top) Turbo Fin Kit is a complete kit designed to upgrade Hobie Miragedrive standard or ST fins to longer 'turbo' variant. Kit includes 2 x fins, 2 x fin masts and fitting hardware.
There are 2 versions of the turbo fin kit available. V1 (pictured above) utilizes a set screw to secure masts into sprockets. V2 (pictured below) threads into brass socket