DORSAL D1 Bamboo Twin Keel Fins are a two-fin set with a classic keel template for a retro fish surfboard. Fiberglass with a honeycomb Hexcore and a wood inlay gives this set its bamboo finish. Fit and setup Compatible with Futures fin boxes. Confirm your board's fin-box system before ordering. Product details Set includes two fins. Size: Large. Color: Bamboo. Material: Fiberglass with Hexcore. Foil: FFT flat foil. Side-fin dimensions Height: 5.01 inches. Base: 6.64 inches. Area: 25.55 square inches.