NO HARMFUL CHEMICALS: Created with durable natural rubber, made by hand, and free of toxic additives such as lead, cadmium, and phthalates. COMFORTABLE: Designed with flexible rubber and lined with 100% soft cotton. ALL-SEASON WEAR: Created with cotton lined insoles for spring and fall, plus bonus micro fleece insoles.NON-SKID SOLES: The rugged design grips on all terrains.