The Dervish is available in two flexes:
Flex 1: 170 lb - 230 lbs
Flex 2: 100 lb - 180 lbs

Keep in mind that a softer flex pattern will give you more control and tighter turns at a wide range of speeds, but tend to lose stability slightly at higher speeds. Stiffer flex means more energy potential and more stability at higher speeds, but will not be as forgiving and lively when cruising.