Muck Boots Rugged Ll Rubber Kid's Snow Boot Synthetic 5 mm neoprene provides comfort and flexibility, along with excellent waterproofing, shock absorption and heat retention properties; adjusts to the shape of little feet to resist blisters and chafing High-grade rubber exterior provides extra toughness and makes for a 100% waterproof snow boot Soft fleece lining provides superior warmth and comfort in extreme cold conditions; comfort rated to -40 F to 40 F (-40 C to 4 C) EVA footbed for lightweight support and cushioning Aggressive, durable outsole for better traction on ice and rain-slick surfaces