Cortex 105 Zonal BOA Women's 25/26
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Built for skiers who don’t slow down when the weather turns or the terrain gets wild, the K2 Cortex 105 Zonal BOA® Women’s Boot is equal parts precision instrument and rugged mountain companion. Designed for hard-charging all-mountain and freeride skiers, it brings a level of fit and control that’s rarely matched—merging race-boot responsiveness with the comfort, adjustability, and durability needed for long, demanding days on snow.
The Cortex 105 Zonal BOA® takes women’s ski boot design to new ground with its dual-zone BOA® Fit System, allowing skiers to fine-tune fit and pressure across the forefoot and cuff independently. The system’s micro-adjustable dials and low-friction lace guides create a seamless, customized hold that eliminates pressure points and enhances power transfer through every arc and edge set.
Inside, the EliteFit Sport Liner provides a high-performance interface between foot and shell. With supportive ankle pockets and a medium-volume fit, it balances stiffness and plush comfort for all-day stability without fatigue. FastFit Instep construction uses softer TPU in key flex zones to make stepping in and out smooth and effortless—even on cold mornings.
The TPU-coated upper and lower shell adds an extra layer of armor against scuffs, moisture, and impact, while maintaining a consistent flex pattern in fluctuating temperatures. Paired with a 45mm cam-style power strap, the boot delivers confident energy transmission from shin to ski, letting you drive turns with race-level precision. The GripWalk® outsoles—preinstalled and compatible with ISO 23223 bindings—offer better traction and natural walking motion for parking lot treks or ridge approaches without compromising downhill power.
Engineered on K2’s MultiFit™ Last, the Cortex accommodates a wide range of foot shapes while maintaining a performance-oriented feel. Whether you’re charging big lines, hunting powder stashes, or carving high-speed corduroy, this boot delivers unwavering control and comfort in every condition.
Features
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BOA® Fit System (Zonal Dual-Zone): Independent upper and lower dials for micro-adjustable, personalized fit and balanced pressure distribution.
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EliteFit Sport Liner: Medium-volume liner with strategic support zones for superior comfort, stability, and rebound.
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FastFit Instep: Softer TPU material in the instep area for smooth, easy entry and exit—even in cold weather.
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TPU Coated Shell (Upper & Lower): Rugged thermoplastic polyurethane coating enhances durability, water resistance, and structural integrity.
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MultiFit™ Last: Adapts to a wide range of foot shapes; designed for anatomical precision without compromising responsiveness.
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45mm Cam Power Strap: Wide, non-elastic strap delivers solid cuff closure and excellent energy transfer at high speeds.
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GripWalk® Outsoles (ISO 23223): Rockered soles improve walking comfort and grip while maintaining full binding compatibility.
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All-Mountain/Freeride Construction: 2-piece shell design optimized for big-mountain performance and variable conditions.
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Medium Flex (105): Ideal balance of stiffness and forgiveness for advanced all-mountain and freeride skiers.
Best For: All-Mountain, Big Mountain, Powder, Speed
Ability Level: Intermediate to Advanced
Flex: 105
Weight: Approx. 1800g (per boot)
The K2 Cortex 105 Zonal BOA® Women’s Boot delivers a rare mix of fine-tuned precision, rugged protection, and dialed-in comfort for serious skiers who demand more from every run. Powerful, intuitive, and ready for anything, it’s a boot that inspires confidence from the first chair to the last lap.
Ski boots are sized in Mondopoint, based on the length of your foot in centimeters. The chart below is a general reference for converting between sizing systems.
This chart is not a fitting. The only way to know your ski boot size is to be fit in person, either with a Boot Fitting at our shop or from a professional fitting you have had elsewhere. Sizing, shape, and volume vary by brand and model, and a performance fit is snugger than your street shoe. Unworn boots can be returned under our return policy, but a boot that doesn't fit can be a big hassle for your trip if you haven't tried it on.
Size Chart
| Mondo (cm) | US Men's | US Women's | EU |
|---|---|---|---|
| 22/22.5 | 4/4.5 | 5/5.5 | 35 |
| 23/23.5 | 5/5.5 | 6/6.5 | 36/37 |
| 24/24.5 | 6/6.5 | 7/7.5 | 38 |
| 25/25.5 | 7/7.5 | 8/8.5 | 39/40 |
| 26/26.5 | 8/8.5 | 9/9.5 | 41 |
| 27/27.5 | 9/9.5 | 10/10.5 | 42/43 |
| 28/28.5 | 10/10.5 | 11/11.5 | 44 |
| 29/29.5 | 11/11.5 | – | 45/46 |
| 30/30.5 | 12/12.5 | – | 47 |
| 31/31.5 | 13/13.5 | – | 48/49 |
| 32/32.5 | 14/14.5 | – | 50 |
Conversions are approximate and can differ by half a size between brands.
Half Sizes
Ski boots are built with one shell for each full and half size, so a 27 and a 27.5 are the same boot with a different liner or footboard. That is why sizes are listed together, like 27/27.5.
Very few models differ from this. Scarpa is the main exception, pairing sizes the other way (for example, 26.5/27 share a shell). When a model is sized differently, we call it out on that product's page.
Book a Boot Fitting with our team at (802) 253-4531. Preliminary boot work is included with every boot purchase.
