I'm 6'1' and pretty lean and got the Medium and felt like the sizing guide was spot on. It fits perfect. The sleeves have a little extra fabric around the wrists to fit under gloves. Inside is some sort of thin fleece or something to help keep warm. I'm honestly a little sad it's warming up and I can't wear this in the SummerI'll get some good mileage out of it in the Spring.
Castelli make nice apparel and this is no exception. Good for cooler to cold days. The sleeves have a little cuff which is a nice touch. Fit is a little small like other Castelli apparel.
Very comfortable, yet form fitting jersey with ample back pockets. Typical Castelli fit, I'm 6'3 235, and wear XXL. I wear this jersey by itself in the 50-60F degree range, but also use it as mid layer under a windproof layer down to 30F. It's a little less substantial than the previous Puro jersey but still very nice. I really like the cuffs as they fit neatly under my gloves.
Good top for cool days. Color is not as blue as it appears in picture. More of a light grey with touch of blue. Also has florescent yellow Castelli printed on arms which is not seen in picture . Typical Castelli sizing. Nice product.. good service from website