This is a burly, insulated, waterproof monster of a mountain boot. The 3.0 mm silicone impregnated Idro-Perwanger Roughout leather uppers are built for adverse abuse. The stiff 8mm MtnFlex insole protects and provides rigidity for automatic crampons. A bathtub Skywalk MPE® sole adds an SBR aircushion platform and sticky all mountain performance.