2.4 mm One Piece Leather: Very durable and comfortably wraps the foot Ball bearing hardware: for easy and precise lacing Double tongue: for improved fit and protection Cambrelle lining: for rapid drying Rubber toe bumper: for additional protection Insole FrameFlex Mid: full length, full width support and protection Crampon-compatible Deeply cupped PU midsole: for better lateral stability and upper protection Vibram IceTrek outsole