There's a lot of technology that goes into the Entrata Jersey. While technically the entry-level jersey in the Castelli collection, it has been engineered to incorporate as much race-level performance as possible while still offering unmatched value. It benefits from the aero learnings from Castelli's race R&D through the one-piece sleeves with aero-optimized seaming. Not only is it aerodynamic, it's also more comfortable thanks to the four-way-stretch Air Mesh fabric and raw-cut sleeve ending that's stretchy to fit every arm without constricting. The main body fabric is just the right weight to keep you cool, while the ProSecco treatment carries away moisture to keep you dry. It's stretchy for great fit and provides UPF 30 sun protection, filtering 97% of UV rays. Thoughtful design and functional details abound, like the stretch panel in the center pocket, the highly reflective insert on the pocket, the full-length easy-sliding YKK® Vislon® zipper, and the silicone gripper elastic to keep the back of the jersey in place.