The Dervish is available in two flexes:
Flex 1: 170-230+lbs / 77-105+kg
Flex 2: 100-185+lbs / 45-85+kg
 
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Keep in mind that a softer flex pattern will give you more control and tighter turns at slower speeds and make it easier to slide, but tends to lose stability slightly at higher speeds. Stiffer flex means more energy potential, more stability at higher speeds, and makes air moves easier, but will not be as forgiving and lively when cruising.