the index – packed with the latest technologies for big mountain missions. the index is packed with the latest technologies and robust enough to conquer any big mountain mission, whether hiking off-piste or embarking on splitboard tours in untouched terrain.outer bootthe index features an asymmetrical upper section that adapts perfectly to your foot and calf thanks to special flex zones. this ensures unparalleled control without compromising comfort. the waterproof storm cover provides extra protection and prevents the lacing from freezing in deep snow. the boot comes with a high-quality b.f.t vibram approach outsole made with icetrek rubber compound for maximum grip on icy surfaces, while a dual layer of eva in the midsole absorbs vibrations on rough terrain and cushions hard landings. the seamless transition zone design merges the outsole with the exo spine, preventing the heel from getting stuck in the binding and transferring more power to the heel edge of your board.inner bootthe heat-moldable gold level wrap liner offers supreme comfort and support.lacingthe index uses a dual-boa® system, allowing you to tighten the upper and lower parts of the boot separately. super fast and convenient. the h4 boa® dials are robust, durable, and easy to use.