VIONIC Mens Whistler Slipper Twin gore across the vamp for comfort and ease of fit. Fits medium width. Fabric and soft faux nubuck upper. Flexible and lightweight rubber outsole with wave-patterned tread helps improve traction. Invented by leading Australian podiatrist- Phillip Vasyli- this shoe features biomechanical orthotic technology that supports your feet and helps realign the lower legs- reducing over-pronation and associated aches and pains. Materials: All man made uppers/liners.