What Our Gearhead® Experts Are Saying:"This boot gives me precision where I want it, and comfort where I need it. The dual BOA system lets me dial the fit separately at the shell and cuff—awesome for all-day resort laps or big mountain lines. It skis like a race boot but without the foot-numbing squeeze."For expert riders who demand power and precision without compromising comfort, the K2 Cortex Zonal 105 BOA® Ski Boot is a game-changer. It’s engineered with freeride and big mountain skiers in mind—those of us who want elite responsiveness and a locked-in feel that won’t leave our feet aching. With the innovative dual BOA® Fit System on both the cuff and shell, we can fine-tune fit on the fly, eliminating pressure points while boosting control. The Cortex 105’s narrow 96–98mm last and 105 flex deliver a race-inspired feel, while the Fastfit instep and low-volume EliteFit Sport liner ensure we can get in and out easily—even with cold fingers. On the mountain, the Energy Bolt spine enhances rearward support, while SES shims let us adjust edge response for fast, fine-tuned skiing. GripWalk soles come preinstalled for confident walking to the lift or the après patio.