The MB2 5-fin is designed by …Lost designer Matt Biolos is a combination of a stiff, drivey thruster designed to provide stability and hold through turns for the larger surfer and a Quad option designed to thrive in his small-wave fun board designs. The wider base of the Quad rears provides hold in wide-tailed boards while the thruster set is ideal for performance surfing. Size: Large (180lb and over) (80kg and over) Front/Center Fins: Height: 4.65" Base: 4.50" Area: 15.45" Rear Fins: Height: 4.22" Base: 4.22" Area: 12.75" Construction: A lightweight hexagonal core gives these fins the feel of glass-ons. Engineered with a medium flex pattern, stiffer than Blackstix but more flexible than Fiberglass. Flat Foil: Flat foiled fins break free sooner, and are better at controlling speed. Often surfers prefer them in fast powerful surf where they do not need to create additional speed. If you have muscle memory from riding glass-ons, flat foiled fins will feel the closest.