The key to the Ereras comfortable & supportive feel is the innovative PU injected Exoskeleton which wraps the heel area without compromising the lightweight & breathability of the upper. This makes the boot feel very stable & supportive without being heavy. The uppers are made from split leather & AKUs amazing Air 8000 fabric. Air 8000 is a lightweight nylon fabric that due to its clever construction breathes 11 times better than traditionally constructed fabric boots. Backed up by a full Gore-Tex bootie lining for complete waterproofing the Arera is ready to tackle all conditions. Vibram have produced the unique Arera sole unit which is durable, lightweight & offers plenty of grip on mixed ground. The internal shape of the boot is dictated by the last, a solid form that the boot is built around & AKU have used an anatomical last which gives room around the metatarsal heads (toe joints) & control & support in the heel area minimising slippage & friction. Flex & stability is provided by the midsole, a nylon board that allows completely natural flexing & an intuitive walking action without being too soft or too stiff. PU injected Exoskeleton Air 8000 uppers Gore-Tex lining Vibram sole