Birkenstock Unisex Boston Soft Footbed Clog Iron Size 41 Leather Upper material: Suede - Thick and supple leathers without additional dyes to keep the leather breathable durable and comfortable. Footbed: Soft footbed - A foam layer is inserted between the cork layer and the suede liner of the original Birkenstock footbed. Millions of microscopic air bubbles cushion your feet while providing moderate arch support. Sole material: EVA - Flexible lightweight durable and shock absorbing.