Purple Performance Glass Thruster FinsOur Performance Glass Thruster sets are designed for any skill level rider that wants to excel in their technical maneuvers. These are a step up from the M21 Polymer Flex Fins. Features: 3k Carbon base Added stiffness on the fin base for more drive Hex Core Moderate flex to maintain speed, add more responsiveness, less resin used for lightweight Flat Foil Gives speed and quick maneuvers Size guide: PG S 120 150 lb PG M 145 175 lb PG L 180 220 lb