I bought the small, which fit my 41" chest perfectly.  It was not snug, nor did it feel or look baggy.  It looked tailored!  I received MANY compliments on the vest and tie at our formal dinner/dance, and we even won best-dressed-couple of the evening.

The vest is well made, with good material.  It is well worth the price, and I intend to pick a couple more in other colors for more options in my formal attire.