Men's Core Seamless Base Layer Thermal Undershirt | Castelli

It's time to rediscover seamless technical underwear. While most technical underwear on the market uses a initially comfortable blend of nylon and Lycra®, it ends up soaked while you're riding, leaving you freezing when you stop. Seamless construction promises stretch and comfort. We've gone the extra mile to ensure this Core Seamless base layer keeps you warm and dry, including the addition of polypropylene and polyester yarns, without compromising the stretchy comfort of the seamless construction. We believe we've struck the right balance, as it also provides a good level of warmth for cool and cold days.