The Rossignol X-9 Skate FW ski boot uses Dual Core Technology to target stiffness exactly where a skating stride needs it, without adding weight anywhere else. That focused build gives a developing skater real power transfer off the push without punishing a less experienced foot for every stride that isn't perfect yet. What Our Gearhead® Experts Are Saying:"My feet stayed warm through a full afternoon on the tracks without the boot feeling bulky. The WinTherm liner seems to send heat back at my foot instead of just trapping it, so I never got that clammy, overheated feeling partway through a session."