Universal, durable and lightweight fins. With the power for scuba diving and the sleek lines of a snorkeling fin, the Express is an excellent choice for warm water. The highly elastic “armadillo” hinge at the base of the blade absorbs energy during the power stroke and releases at the end of the kick cycle to maximize thrust. The blade is attached to the foot pocket using the Mid-Foot Flex Joint for efficient energy transfer and reduced leg strain. Features: Customized techno-polymer alloy blade has a high spring effect and flexibility for excellent responsiveness and acceleration, Armadillo membrane at the base of the blade absorbs energy during the power stroke, and releases prior to the upstroke for a power boost on every kick, Rubber side ribs channel water down the length of the fin, minimizing wasted energy from the spill-over effect, A Mid-foot Flex Joint is used to attach the blade to the side of the foot pocket for efficient energy transfer and reduced strain on the ankles and toes, Ergonomic foot pocket uses rubber of varying elasticity for a natural fit and comfortable, efficient kicking, Integrated power transmission belt keeps foot pocket from stretching on power stroke, Anti-slip rubber pads on the bottom of the foot pocket provide traction for moving around on boat decks, Color: Black/Blue, Size: 40/41