I use the product for swimming. It''s great because it keep my upper body warm and makes it  easier to get in the water. It''s very light and easy to put on.  The thing I don''t like is the bottom cord doesn''t have clip to keep it tight. Other wise it great .

I can only comment at this point on the fit but was pleased that it did fit okay since most of the reviews had said it ran way too small.  I am normally a size 10 to 12 and the 12 fit fine, these types of things are always hard to get in and out of but once on, it feels like the right fit.  Just haven''t had a chance to try it out in the water yet but it does fit under or over my sleeveless shorty for fall skiing/kayaking.  The price was great too at Swim Outlet and can''t go wrong with O''Neill stuff.

Runs very small.  Not a good fit for petite, large busted women.  If it fits, would probably do a good job of keeping you warm in cold weather/water.  I returned it and opted for a zip up jacket style.

I wear a 12 or 14 & so I ordered a 14.  I got it on but couldn't get it off without help.  I had to return it!

Nice top.
But not for a lady - way way too small.
Size 14 was more like a size 6.
Definitely do not order if you have larger breasts.

The problem is it IS too big, yet it FEELS too small.  I'll explain.  It is VERY difficult to get on and off, painful in fact in the shoulder muscles.  However, once on, there is a lot of extra fabric in the arms which are too long, and it balloons underwater so that it does not insulate.  I probably need a medium instead of a large, but I don't know whether I could get it on and off.  I would suggest designing a swim jacket with a full front zipper, and perhaps some sort of fabric which has more elasticity.  I'd like to exchange this one for something more comfortable, easier to get in and out of, yet insulates.  This just doesn't work for me.