When Castelli engineered the first aero jersey for road racing back in 2006, everyone thought we were crazy. Back then, aero was only for TTs. Performance clothing meant moisture management. & you could win the Tour de France with a baggy jersey that was little more than a polyester T-shirt. Even our aerodynamic consultants expected limited gains, so we named the jersey Split Second, though, like now, we thought even small gains were worth pursuing. In the end the gains were pretty substantial, & we completely revolutionized the look of the pro peloton. We're now on the sixth major revision of our aero jersey. Each generation has become more aero & better fitting. The Aero Race 6.0 benefits heavily from CFD analysis of wake flow in the riding position for fabric & seam placement. It also benefits from Team Ineos riders' feedback, as we've worked to make the jersey comfortable for their long hours of training & then racing in every possible weather condition. Version 6.0 is our most aero & most comfortable Aero Race Jersey yet. But we're already at work on 6.1... Features CFD-based fabric placement & seam construction Engineered for aero efficiency at 30 to 55 km/h Airflow shoulder construction Velocity Rev 2 fabric on front & sleeve 3D mesh back for breathability Elbow-length stretch sleeves with raw-cut edge YKK® Vislon® zipper Drop tail allows perfect pocket placement while keeping jersey fitting well at waist 18°-32°C / 65°-90°F Weight:119g