The Castelli Pro Thermal Mid Jersey is a minimalist, close-cut aero jersey that nonetheless provides a bit of warmth when there's a nip in the air.
Constructed from mid-weight Warmer X-Stretch brushed fabric, it is soft and cosy against the skin, but includes just enough elastane to achieve an effective, comfortable race fit. It goes nicely under a vest if you're feeling the chill and has three drop pockets to store that vest in.
Add in a smooth-running zipper and a reflective strip at the back, and you have a light, aerodynamic short sleeve jersey with a bit more warmth than is typical, boasting the features you need and none that you don't.