What Our Gearhead(R) Experts Are Saying:"This is one of the lightest, most breathable jerseys I have ever worn on a hot climb. The Flusso 3D front and StradaPro 3D back work together to move sweat out fast, and the airflow shoulder construction makes a noticeable difference when you are deep in a long effort on a hot day. My go-to pick for summer racing and high-intensity training when the temperature is not doing you any favors."The Castelli Soudal Quick Step Climber's A/C SS Jersey was built around a single premise: when the road tilts up and the heat is working against you, your kit should not be. Developed for high-output efforts in extreme temperatures, it pulls from CFD-based fabric placement and seam construction to put the right materials exactly where airflow and moisture management matter most. The result is a jersey that actively works to keep you cool rather than simply staying out of the way. Castelli spec'd Flusso 3D across the front panels for optimized ventilation where sun exposure is highest, and StradaPro 3D on the back to pull sweat away at speed before it has a chance to slow you down. The airflow shoulder construction opens up cooling across the upper body during the sustained efforts that define long alpine climbs and midsummer road races. Elbow-length raw-cut sleeves trim drag without adding bulk, and the form-fitting race cut keeps everything locked in close to the body where aerodynamics are won and lost. A full-length YKK Vislon zipper lets you manage ventilation on the fly, and the elastic waist keeps the jersey seated and pockets accessible no matter how hard you are pushing.