MEPHISTO HELENKA | Women Cork Sandals Leather Nubuck. This light thong is a must-have for a casual summer. The unique SOFT-AIR technology, integrated in the midsole, guarantees an effortless walk. The AIR-RELAX technology respects the anatomy of the foot to prevent fallen arches. The adjustable buckle on the instep offers an excellent fit. This model stands out thanks to the metallic ornaments on the front of the foot.