Though a short-sleeve jersey, the Castelli Pro Thermal Mid Short-Sleeve Jersey is built for a bit of extra warmth when we head out for a ride in cooler conditions. It features a mixture of mid-weight brushed inner fabric and stretchy elastane, allowing for a close fit to our body for a warm, comfortable ride. On colder days, we add arm warmers and a light vest, while a reflective stripe keeps us visible when we get caught in the dark.