Castelli Cold Days 2nd Layer Top Hombre, azul

Maximum insulation and moisture management for cold rides, to layer between a base layer and a jacket.

Polartec Alpha
Polartec Alpha was invented for the U.S. special forces. They required a superior insulation system for extreme temperature variations and the start-stop conditions of combat. Alpha active insulation is engineered for consistent warmth, while allowing greater breathability during activity. This air exchange technology creates sustained comfort without shedding layers, which isn’t an option during a mission.