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The first biotech ski socks for racing performance. Made from 80% kapok, the lightest natural fiber in the world, and plant-based materials, the Ski One Biotech socks fit the foot like a second skin and support its natural functions. Kapok provides exceptional heat regulation, while the Biolight fiber from beech increases durability and breathability. Natex made from castor seeds allows the sock to dry 50% faster. The result is perfect temperature management for feet that are always dry and ventilated. Ski One Biotech socks are made with Zerocuff technology, which has no elastic at the top for greater comfort and better blood circulation.
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UYN Size Chart
Fit-und-Warm carries UYN for Casual, MTB, Road Cycling, Running, Trekking and Winter Sports for women, men and children. Relevant products include base layers, T-shirts, jackets and socks. UYN uses strongly product- and activity-specific apparel fits.
Unisex / Men's Socks
| EU | Foot length (cm) | US Men | UK |
|---|---|---|---|
| 35–38 | 23–24 | 4–5.5 | 3–5 |
| 39–41 | 24.5–25.5 | 6.5–8 | 6–7.5 |
| 42–44 | 26–27 | 8.5–10 | 8–9.5 |
| 45–47 | 27.5–28.5 | 11–12.5 | 10.5–12 |
Women's Socks – On Models Labelled Accordingly
| EU | Foot length (cm) | US Women | UK |
|---|---|---|---|
| 35–36 | 22.5–23 | 4.5–5.5 | 3–3.5 |
| 37–38 | 23.5–24 | 6–7 | 4.5–5.5 |
| 39–40 | 24.5–25 | 7.5–8 | 6–6.5 |
| 41–42 | 25.5–26 | 9–10 | 7.5–8 |
Apparel
| Area | Current official size selection |
|---|---|
| Men's technical apparel | XS to XXL; some products use combined sizes |
| Women's technical apparel | 2XS to XXL; some products use XS/S, S/M, M/L, L/XL |
| Fits | Aerodynamic / Slim / Regular / Comfort |
UYN provides the concrete size chart directly with each product. Because base layer, cycling, running, trekking and winter products use different constructions and fits, no third-party universal body chart is added.
Assortment check: Fit-und-Warm UYN brand page. Manufacturer sources: official UYN apparel categories/fit information and product-specific UYN sock size charts. Research checked on 20 August 2026.