The new Caicos fin has an extended sole plate, which adds thrust and relieves strain on your foot. Simple and reliable strap adjustment system. Contoured foot pocket for maximum comfort. Fins can be used with or without booties/fin socks. The directional channel, in the middle of the fin, increases propulsion efficiency. Vent spaces, on each side of the fin, releases water not involved with thrust. SIZES: XS 1-4, SM/MD 4 1/2-8, LG/XL 8 1/2-13. AVAILABLE COLORS: Blue, Yellow, Pink and Magenta