I'm sure O'Neill makes great stuff. Never owned anything from them. Was hoping this would be my first. Like others suggested I went up a size just in case. Piece of advice, don't be fat if you want to wear this. I mean, at all! I'm about 230lbs 6'2" and typically wear XL. At XXL this thing was choking me all over. Especially the shoulders. I found it very difficult to get in and out of this rash guard. I have a Nike brand rash guard I've used for years and it is way more flexible, just as breathable and wicks moisture just as well. In XL, not XXL. Other than fit I think the construction was very well done. Just wish it fit me so I could've kept it.