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The UYN BIOTREK LIGHT hiking socks have been developed so that you can experience every hike in full harmony with nature. Made from the exclusive bio-based COOLTH_SL material, which keeps your feet dry even on the hottest days thanks to its high sweat-absorbing properties. An unprecedented feeling on your feet thanks to the bio-based material composition: soft and comfortable, with top performance and breathability.
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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.