Just got this in the mail... fabric is breathable and lightweight, but still sturdy. Great gripper on the back hem keeps things from riding up and sleeves fit well without giving you "arm chub". As with most Castelli products, sizing up is recommended. I wear a medium normally, but bought a large and it fits like a glove (in a good way!). All in all a great buy.
Consider this purchase another way to support American cycling!