OOFOS Unisex Ooriginal Thong Sandals,Black,13 M US Men / 15 M US Women Synthetic Made with the patented OOfoam - soft, durable, provides extra-cushioning, and shock absorption. Reduces the impact of walking on hard, unnatural surfaces to help prevent foot fatigue. Great for plantar fasciitis as the footbed conforms to your foot to provide customized support. Great for arthritic feet as the footbed is soft and super shock-absorbent. OOfoam is easy to clean, it does not absorb water, is machine washable and is water resistant