After starting the aero jersey revolution in pro cycling, Castelli have continued to perfect this piece. Team Sky Inside 5.1 Jersey builds on the race-leading aerodynamics while making the jersey more comfortable and durable. Updated fabrics on the front and back showed a 2-watt gain in the wind tunnel compared to the previous version. But it's not just aero; it's also extremely light, coming in at just 103g. That's about 40g lighter than a standard jersey and almost as light as our Climber's Jersey. Just like you, Team Sky pro riders are looking for comfort, and the lightweight polyester fabrics in this jersey dry nearly instantly, making this the go-to choice even for cool or wet weather racing, while the compression band around the pockets keeps them from moving or bouncing no matter how you load them up.