I love the feel of this top - used it in my last Ironman but it runs very small. I bought a SM originally and felt really tight. Then bought a MED and it was only a tiny bit bigger, maybe a tad longer is all. I typically wear a SM - I am 5'3 and 115' with 34B chest - fyi. ALSO - I lost a flask in the side pocket - being so tight things pop out!