Aero jerseys are great in high speed situations where wind resistance is the main concern, but they aren't always very comfortable on the climb. The Castelli Climber's 2. 0 Full Zip Jersey was designed to provide the best of both worlds an aerodynamic jersey that's cool enough to wear on the climb. To achieve this goal, Castelli stated with the cur from its Aero Race 5. 0 jersey. The cut is aerodynamic, but Castelli's jersey are famous for their comfort while in the seated position. With the pattern ready, Castelli then used cool, lightweight fabrics to eliminate overheating. The front panel is made with Flusso 3D, a lightweight, extremely breathable fabric that moves moisture away from your skin to the surface of the fabric to evaporate. The back panel is StradaPro 3D polyester. It also breathes well and manages moisture, but it was chosen because it lends structural stability to the three back pockets, as well as a bit of sun protection. If you need to dump heat in a hurry, the full length front zipper should provide all the ventilation you'll need.