The Castelli Flanders 2 LS Base Layer is designed as the ultimate foundation for cold-weather riding, offering premium insulation with a mid-height collar for added warmth and comfort. Built from SottoZero multi-denier 100% polyester fleece, it delivers outstanding thermal regulation while maintaining excellent breathability to keep you dry during intense efforts. Weighing just 181 grams, it provides lightweight warmth without compromising mobility, making it ideal for temperatures ranging from -2°C to 10°C (28°F to 50°F). Flat Merrow stitching ensures a smooth, irritation-free fit against the skin, while mesh armpit inserts enhance ventilation in high-heat zones to prevent overheating. With a regular fit that balances close-body efficiency and all-day comfort, the Flanders 2 LS Base Layer is engineered to keep you performing at your best through the coldest conditions.