The Mistral Challenge Flex is a one-of-a-kind sailboard design that offers the ability to install a shorter or longer tail for different sailing conditions. The flex of the tail is also adjustable. I preferred the long tail and that's what's installed in the pictures. The shorter tail works but is missing the right side molded foam piece. I also have an additional long tail that is missing both black foam pieces and has a broken fin box (see pictures). I also have a boom, sails, and other hardware that could go with it.