Cold Days 2nd Long-Sleeve Baselayer - Women's

What Our Gearhead® Experts Are Saying:

"The Cold Days 2nd Long-Sleeve Baselayer is the mid-layer I recommend without hesitation for any rider committed to training through deep winter. Polartec Alpha is the right fabric choice for active insulation at this temperature range, and the 153g weight is genuinely impressive for how much warmth it delivers. The half zip gives you real ventilation control on the climbs, and the fit integrates cleanly with any base layer and jacket combination in the Castelli lineup."

The Cold Days 2nd Long-Sleeve Baselayer from Castelli is the full-coverage version of Castelli's active insulation mid-layer concept, purpose-built for the 17 to 41 degree Fahrenheit range where a single base layer runs out of answers. Polartec Alpha fabric delivers the same soft, stretchy, lightweight insulation found across the Cold Days lineup but with complete arm coverage for conditions where core warmth alone is not enough.

At 153 grams, the garment adds meaningful thermal performance without creating bulk under a jacket or restricting movement through the shoulder and arm. The half zip sits at the neck for ventilation management on climbs and harder efforts, allowing riders to regulate temperature without removing a layer mid-ride. The regular fit accommodates a close-fitting base layer underneath and sits cleanly under any Castelli winter jacket on top, making it a reliable anchor for a complete sub-freezing layering system.