This jersey is an evolution of Castelli's pro racing jersey from just four years ago. It's also Castelli's first aero race jersey that didn't get retired when the next generation of faster, more aero jerseys came along. The aero race 4.0 jersey was very fast but also an amazing mix of classic good looks and a stretchy fit that works on a lot of body types, not just the skinny racer. For the 4.1 version Castelli have taken a different direction, away from pro racing. By giving it the conveniance features that seamed superfluous when Castelli designed the 4.0 to win the Giro D'Italia. This updated jersey gets a zippered rear pocket, a flap behind the zipper to protect your neck, updated velocity dimpled fabric on the front and an angled pocket for easier access.