This is a very useful style, especially for spring and summer. The bra comes with an extra hook, so the straps can be converted to a racerback style. And, the double shoulder straps are pretty enough to let show while wearing a tank top.
It's a contour style bra, designed to "dramatically enhance cleavage," according to the manufacturer, if you use the included removable pads. (But I think that the pads are only a good idea if you're an A or B cup size).