Racing in the Alps in July is for a select few, but the products that come out of that experience are absolutely amazing for the rest of us. We made this jersey for hot days in the high mountains, based on direct feedback from the pros. They wanted a jersey to keep them cool on hot days without sacrificing aerodynamics. The Climber's 4.0 Jersey uses the same CFD-based seam construction as our Aero Race 8S Jersey, but we've used the most aerodynamic 3D mesh fabrics we could find for optimal cooling. These fabrics also have a great soft and stretchy quality to them, giving this jersey a comfortable fit too, which you need for big days in the mountains. And since this jersey is meant to be used in the sun, we've also made sure the fabric on the back blocks 90% of UV rays.