Leather and or fabric uppers Padded instep collar for comfort when walking Roomy reinforced toe box for protection with plenty of "wiggle room" for your toes PU outsole with rocker bottom to propel foot forward and provide shock absorption Wide heel strike for greater stability Sonja is a traditional open-back clog that features a roomy reinforced toe box, an anatomically contoured PU midsole, an inner frame for stability and support, a padded instep collar, and an anti-fatigue rocker bottom that enhances forward motion while walking.