Best vest I've owned so far. I'm 5'9" with a 39" chest and the L is a perfect fit: very snug but not constrictive. I hate it when vests flap in the wind so I wanted the "race" fit. Once it's on over my jersey I hardly even know it's there. It's even fairly snug (but not tight) around the neck, so there's far less wind that sneaks in through up top. And as others have mentioned, it rolls up incredibly small.
One other note on the fit: the arm holes are elastic and somewhat tight. Which I like; again, one less spot for the wind to sneak in. I've noticed that if you're standing it'll feel like the bottom of the arm holes are riding up into your armpits, and I was definitely nervous when I tried this vest on the first time thinking this was really going to bother me. However, once in the saddle in the crouch position I've experience no discomfort whatsoever.
Definitely a great looking vest and a solid windstopper. I've had no issues with the material or zippers either and have been using this vest 2-3 times a week for the last couple of months. (I live in SF, it's always cool here.) The side zippers are a nice touch. But like tom5024396 mentions there are two key drawbacks:
1) Without ventilation you really do sweat in this vest. You can open the side zippers for a little help but not much.
2) I found the sizing to be off as well. I wear a large in Castelli jerseys which fit great but this vest (in large) is cut a little big so there's some flapping in the shoulders on descents.
Does this come with the 2 screws for mounting or is it just the cage? Thanks.