The Fastalpina GTX is a well designed & proper walking & trekking shoe that has been designed to be used for longer walks & treks. The key to the Fastalpinas comfort & support is the ingenious IMS 3 system. IMS 3 combines the outersole, an exoskeleton support structure & a 3D anatomical fit midsole. The outsole is exclusive to AKU & is a lightweight deep lugged Vibram unit combining durability with traction & stability. Cushioning & support is provided by the internal PU & EVA midsole which then extends up & around the heel to provide additional support & pronation control. The IMS 3D midsole provides a natural rolling flex to the boot without it being too soft or too stiff. The design of the midsole itself mimics the foot shape to cradle the foot in a natural position reducing fatigue & internal movement. The internal shape of the boot is dictated by the last, a solid form that the boot is built around, & AKU use a special anatomical last which gives room around the metatarsal heads (toe joints) & control & support in the heel area minimising slippage & friction. AKU are one of very few manufacturers to make their boots with the last inside the shoe throughout the production process. Whilst this may take longer, & increase cost, it does ensure the shoe retains its shape integrity, resulting in a fit that remains true for the life of the shoe. To further enhance your comfort & security the lacing system uses rollers to allow an even & smooth lace pull eliminating tight spots. The uppers are a mixture of leather & synthetic materials to provide durability & breathability. The synthetic material is a 3D Air Mesh, an incredibly breathable material that helps to keep your feet cool, this is then fully Gore-Tex lined for complete waterproofness. All together the Fastalpina is a supremely comfortable & high performance walking & trekking shoe suitable for walking in varied terrain & for longer treks in the mountains. Custom Vibram sole unit Suede & 3D Air Mesh uppers Gore-Tex lined PU Exoskeleton IMS 3 support system