Spanx Slim Cognito Midthigh Nude Bodysuit Spanx is extremly popular because these shapers are comfortable to wear and really make a difference in how your clothes fit. This really holds you in and makes you feel great in your dress/outfit, whatever you're wearing!! The world's first performance underwear combines the comfort of regular underwear, the feel of hosiery and the power of a shaper. Plus, there's no binding legband to create bulge on your thigh!