TwinTrail – Women’s Medium-Warmth Double-Zip Fleece Base Layer

Meet the Beneunder Fleece Outdoor Base Layer — available in two warmth levels to adapt to different temperatures. Crafted from double-brushed fleece with high-stretch fibers, it keeps you warm without bulk and moves with you effortlessly. The fabric’s quick-dry technology wicks away sweat, while the slim fit layers easily under jackets or stands alone. Choose the Mid-Warmth version for 5°C to 15°C, or the High-Warmth version for -5°C to 5°C.

Highlights:

• Double-brushed fleece traps heat, +1.9°C to +2.1°C warmth boost
• Hollow-core fibers lock in warmth with 37.8%–44.1% better heat retention
• Two warmth levels: Mid-Warmth (5°C–15°C) / High-Warmth (-5°C–5°C)
• 3.4× stretch with 360° mobility, no tightness
• Sweat-wicking and quick-dry comfort for all-day wear
• Lightweight slim fit, easy to layer without bulk