The key to the Transalpinas 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 shape of the midsole itself mimics the natural 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 an anatomical last which gives room around the metatarsal heads (toe joints) & control & support in the heel area minimising slippage & friction. The uppers are a mixture of leather & synthetic materials to provide durability & breathability. The synthetic material is made from Air 8000, an incredibly breathable material that breathes 11 times better than traditionally made fabric boots. Fully Gore-Tex lined for complete waterproofness. All together the Transalpina is a supremely comfortable & high performance trekking boot suitable for walking in varied terrain & for longer treks in the mountains.