The first thing you notice about these incredible boots, apart from how drop dead gorgeous they are, is how amazingly light they are for a fully technical B3 rated boot. The original Nepal boots were incredibly robust & long lasting, but weighed a ton, the new Nepal Cube GTX carries on the tradition of durability & reliability but at a fraction of the weight. They are made using fully insulated high quality Idro-Perwanger leather. This is a premium silicone impregnated 3.2mm rough-out leather made by Perwanger Leather of Italy. Perwanger has been making leather in the Southern Tyrol region of Italy since 1780 & tans their Idro-Perwanger hides with a special process to make them extremely water repellent while still retaining maximum breathability. This leather is the most durable available & is made from the corium, the strongest part of the leather. This high quality & incredibly robust leather is then backed by a fully insulated Gore-Tex membrane to provide the warmth needed on high altitude expeditions & the complete waterproofing needed when ploughing through wet snow. When you slip your feet into these beauties you instantly feel secured & cosseted by the internal heel & ankle padding, giving you the confidence that any suggestion of heel slip, which can be a problem with B3 boots, will be eliminated. Full ankle articulation is provided by the innovative 3D Flex System at the ankle which makes long walk-ins possible & makes these incredible boots comfortable enough for general mountaineering, despite their B3 rating. Further comfort is achieved by the EZ-OUT variable adjustable tongue; mesh covered foam is adjustable to fit & also acts as a pump to draw moisture out of the boot. The lower part of the uppers are protected from scrapes & abrasion by an air injected rubber r&, this process reduces weight & allows for a very precise & custom application; which is why these boots look so damn good. The toe area, which gets the most abuse, has a tougher material overlay. Underfoot there is a Carbon Tech honeycomb midsole which provides the strength & stability for the boot & also insulates without adding unnecessary weight. A 4mm layer of EVA foam enhances this insulation & adds shock absorbency & cushioning. To enable a secure & safe crampon attachment a 2mm Polyurethane layer runs through the midsole enabling all types of crampons to be attached. Finally a replaceable Vibram sole with aggressive lugs & La Sportivas brilliant Impact Brake System (IBS) provides grip & security on all terrain. IBS is a unique technology in outsole design where the lugs of the soles are oriented in opposing slanted directions. This opposition increases braking power & decreases impact forces by an average of 20%.