The F4 Blackstix fin is one of the most balanced templates we offer, making it one of the most popular fins in our lineup. The springy flex pattern of the Blackstix construction combined with the V2 Foil give this fin a lively feel, making it an ideal choice for generating speed and increased drive in smaller waves while the thicker tip provides hold when you?re on rail.--CONSTRUCTION-BLACKSTIX-Blackstix have a flexible Carbon Fiber tip that loads up and releases energy for generating speed when you need it. These are the lightest fins in the Futures line.--FOIL-V2 FOIL-A V2 Foil is a V. Foil and Flat Foil blend. It takes the best speed generating attributes of the V. (at the base) and transitions into a flat foil in the tip for a controlled release in critical turns. Try the V2 foil if you are transitioning from flat sided fins. The benefits of the V. foil base will be noticeable but the change for your muscle memory will not be too drastic.