Castelli Core Seamless Base LayerCreated to keep you warm and sweat-free, the Castelli Core Seamless Base Layer makes cycling in colder weather more comfortable. While it may feel light in weight, the Core Seamless Base Layer is still remarkably good at keeping you warm. And while it provides a layer of insulation it also rapidly wicks away sweat too, vital for comfort even when you're cycling in colder weather. The seamless construction makes it feel great against the skin while a wide neck works well with short-collared long-sleeved racing jerseys. It's a great pick for racing and training early or late season. Features:Materials: 84% Polyester, 16% PolypropyleneYarns provide soft, warm wicking and exceptional stretch fitSeamless construction means extra comfortLighter weight on side and backWide neck opening to fit under short-collared jerseysSuggested temperature range: 4 to 16 degrees CBuy Castelli Clothing from Chain Reaction Cycles, the World's Largest Online Bike Store.