Boreal's Kangri Bi-Flex Mountaineering Boot isn't just built to withstand the tough conditions you'll encounter in the alpine--it's a boot designed to deliver a comfortable and easy-flexing feel whether you're roped up during glacial travel or working up a vertical crux of rock and ice. Versatile single boot construction makes the boot suitable for use on all but the world's highest peaks thanks to its Boreal Dry-Line waterproof and breathable membrane and triple-layer Thinsulate insulation for 360-degrees of foot warmth.What really sets the Kangri Bi-Flex apart from other boots in its class, though, is the addition of Boreal's VTS tongue system. The tongue combines a traditional lace closure, neoprene cuff, and hook-and-loop adjustable tongue that can be dialed in to ensure a precise and comfortable fit around the leg. Boreal even added its Bi-Flex system, which consists of soft compressible panels for progressive forward flex for easy walking. Boreal built the Kangri on a Vibram Teton sole for solid and reliable traction and added a lightweight carbon composite midsole for a stiff, responsive feel when front pointing. Boreal even integrated layers of EVA and PU for better shock absorption when climbing on rock and ice.