The 'X-UP' is what you order when you want a short board with a bit more holding power. Think a short board with a slightly pulled in tail and that is what the 'X-UP' is. The X-UP'S will hold in a bit better than the regular short board, but no maneuverability will be lost because of added length to the board. Often these boards are ordered 1 to 2 inches taller than other shrotboards and are used in surf that is head high to double overhead. The X-UP's are available in all of our short board models. Just ask for the 'X-UP' version.