Recommended for boards with deep concaves and moderate-to-extreme rocker, the FCS Carver Neo Glass Quad Rear Surfboard fins are designed for powerful, drawn-out turns and excel out on open face waves. Made from lightweight yet sturdy molded-fiberglass Neo Glass, these fins have an elongated shape for performing long-arcing slashes, and a high-degree sweep angle for exceptional control off the bottom and when carving on the open face.