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The right gear can make all the difference in your outdoor experience, and with the UYN BIOTREK socks, your feet will experience a feeling you've never experienced before. Made from a combination of the most advanced protection and moisture management technologies, along with innovative bio-based materials such as NATEX, which provides extreme lightness and quick drying. Combined with the advanced hydrophilic properties of ECOLYPT, your feet will stay dry, cool and protected even after hours in the great outdoors.
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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.