I ordered a LG in this (normally wear sz 8), because I didn't want it to be too tight (which I tend to find most rashguards are for me). It feels great. One thing I would mention that I didn't realize when ordering--this has a built in shelf bra. I had planned to wear this over a swimsuit and still can, but the shelf bra also means I can wear this without a swimsuit. So while I at first wasn't sure I liked the shelf bra, it has turned out to be a bonus. Also, for some reason on my home computer the color of the sleeves looked teal/turquoise, the sleeves are definitely a green (kind of kelly green). Love, love the sleeve length!!! This sleeve has been very hard to find, but is perfect.

The neckline is bigger than regular rash guard shirts.  The black sides are slimming.  The sleeves are comfortable--not too tight.