Built as a lightweight top for those rides with plenty of elevation, the Climber's Short-Sleeve Jersey from Castelli is the one to wear when the road turns up. Its no one trick pony though, and we've found it works well in hot weather and is an ideal base layer in cooler weather or rain under a vest or jacket thanks to its minimal moisture absorption. The inner lining keeps things modest and adds a nice design detail to this highly technical jersey. Castelli employs 3D fabric architecture throughout its line, and the Climber features Flusso 3D on the front and shoulders and StradaPro 3D on the back. Flusso is so light that you'll hardly notice it, and Strada Pro is hyper-efficient but has a little more structure to support the three pockets on the back of the jersey. Both wick moisture and breathe exceptionally well to keep you cool and dry. Castelli also engineers the Climber with a built-in bustier lining for comfortable support. AirMesh armbands keep your sleeves in place and provide an aerodynamic fit, and the 3/4-length zipper reduces bulk for an uninterrupted, smooth surface over the jersey's stomach.