There is not a ski mountaineering boot on the market that skis as well as the Radium. It is truly the best of both worlds - touring and skiing. It is light and very easy-walking, yet as stiff and responsive as an alpine boot. The Radium"s unique overlap design allows the cuff and lower shell to function very independently when hiking, yet it buckles down securely to descend like the best alpine boots. Its responsive multi-injected lower shell and cuff are built from Pebax for the lightest weight and least temperature sensitivity.