The X2 is the latest version of the World Standard FCS system featuring a new dramatically stronger material. X2 is 40% stronger than the existing P2 plug. It is the lightest and strongest high performance fin system available in the world today. FCS has done extensive testing by breaking hundreds of systems and comparing the results in specially made cassettes that replicate the rail section of a surfboard. X2 offers all of the benefits of FCS, with 40% more strength. The X2 is a custom blend of nylon and glass fiber.