Matt Mwrote a review of Castelli Puro 2 Jersey - Men's on January 3, 2017
Familiarity: I've used it several times
Fit: Runs large
Awesome Fall Jersey. Light fleece lining. Great for temps in 60s IMO. Doable to 70 or upper 50s. Note that unlike other Castelli tops, this one runs a bit more "loose". Many complain about their sizing but if you match up their scale properly, fit is accurate. It has very little to do with other manufacturers mind you.
I'm a 42in athletic sport coat fit. Castelli XL = 41.3in and XXL=43.3in. I've found this to be spot on. Race Fit Items like their Climbers jersey are painted on me in XL and ever so loose in XXL.
With the PURO Jersey the XXL is almost too loose. The XL is the better fit with proper sleeve length. I have 35" arms and the XXL is a tad long.