Kids Arctic Sport Muck Boots rubber Breathable Airmesh lining that allows air to circulate provides superior comfort and breathability by wicking away humidity and perspiration CR-Foam bootie construction, this extreme comfort construction is lightweight, flexible, bouyant and 100% waterproof top to bottom. With the flexible upper, the pant leg can be worn over or inside the boot Natural Rubber upper overlays, not TPR or PVC vulcanization binds the rubber pieces together to form an extremely durable and lightweight shell. The rubber shell and nylon upper are very durable and clean up easily with a spray of water or a gentle scrubbing with soap and water