Portlandia Solar Strappy Sandals Soft, leather upper features two hook-and-loop closures, one on the ankle and one on the instep, which helps hold your foot in place and offers a just-right fit. Natural cork midsole, made of eco-friendly, biodegradable materials, conforms to the shape or your foot. Durable rubber outsole delivers sure-footed traction. Heel Height: 1. Material Content: leather upper and upper lining, synthetic sockliner, cork footbed and midsole, polyurethane shank, rubber outsole.