What a great product. I own quite a few Castelli, Primal and PI jerseys, this is my favorite. This is the 2011 in-R-cool version too. The fabric is thin, durable and almost silk-like, but it's better! I have larger biceps and this is one of the few jerseys that actually doesn't choke my arms into submission. Bought the XXL version at 6'00, 220 lbs. Came back and bought the white/black version too. Just as a point of reference, I wear XXL in Primal, XXL in PI, and 3XL in Castelli jerseys.