The D2 gets its shape-shifting abilities from flexible rubber inserts that run down its center, eight inches in from either end. When a skier begins to turn, he slows down, putting extra pressure on the skis. This force stretches the rubber, increasing the width of the tip and tail by about one sixth of an inch (a hefty amount for a ski that's just 4.2 inches wide). With more of an hourglass shape, the ski naturally slides in a semicircle so that you can turn with less effort. As you straighten out of a turn, removing pressure, the ski contracts, its arch and surface area shrink, and it rockets straight to the bottom.