Dont overengineer it just make it right that was the goal of castellis product team in making their new castelli entrata 2 short sleeve full zip jersey start with a great fabric one that looks good and keeps you dry and comfortable then use a lightweight and very stretchy mesh on the side panels for extra give and in the shoulders for great fit whether youre standing or in an aero tuck get all the details right like the easy sliding ykk vislon zipper and reflective trim at the hem for