This is essentially the top half of the Sam Remo Speed Suit. I have lots of Castelli medium size clothing, so this a bit of an anomaly. I wouldn't have gone larger, but I could barely get the sleeves over my elbows. Size up if you have any doubts. Absolutely spray on. It necessarily has a strong zipper. I'd recommend the San Remo as an alternative as the overall aero effect is better. Good quality, but watch the sizing.
Bought this jersey as part of my summer go fast jerseys. I love the way it feels and you do feel faster after you suit up!