8mm CR flex-foam bootie with four-way stretch nylon. 100% waterproof, lightweight and flexible. Fleece Lining. Bob-tracker molded outsole is rugged, aggressive and durable for maximum protection and stability. Double reinforcements on the instep, heel and achilles. 2mm thermal foam underlay added to the instep area for additional warmth. EVA molded midsole with contoured footbed.